Monumental rock art illustrates that humans thrived in the Arabian Desert during the Pleistocene-Holocene transition

Domain: earth_science
Published: 2025-09-30
Editorial outcome: major_revision

Abstract
Dated archaeological sites are absent in northern Arabia between the Last Glacial Maximum (LGM) and 10,000 years ago (ka), signifying potential population abandonment prior to the onset of the Holocene humid period. Here we present evidence that playas became established in the Nefud desert of northern Arabia between ~16 and ~13 ka, the earliest reported presence of surface water following the hyper-aridity of the LGM. These freshwater sources facilitated human expansions into arid landscapes as shown by new excavations of stratified archaeological sites dating to between 12.8 and 11.4 ka. During the Pleistocene-Holocene transition, human populations exploited a network of seasonal water bodies - marking locations and access routes with monumental rock engravings of camels, ibex, wild equids, gazelles, and aurochs. These communities made distinctive stone tool types showing ongoing connections to the late Epipalaeolithic and Pre-Pottery Neolithic populations of the Levant.

Introduction
At the end of the last Ice Age, the Last Glacial Maximum (LGM, ~25–20 ka) ushered in harsher, cooler climatic conditions that resulted in extreme aridity across the Middle East, causing widespread dune mobilisation and de-population on the Arabian peninsula1–4. In the “Fertile Crescent”, the Pleistocene-Holocene transition brought a return to more favourable climatic conditions. The Natufian (~14.6−11.5 ka) is associated with intensive plant exploitation, and the widespread adoption of sedentism and food storage1,2,5. The domestication of plants and animals commenced in the Pre-Pottery Neolithic (PPN) A and B, respectively (~11.7–10.5 ka and 10.5–8.25 ka)1,6–8. These pronounced socio-economic shifts went hand in hand with the emergence of a rich symbology expressed in carvings, figurines, and architecture1,9. Notably, distinct geographic differences formed across the late Epipalaeolithic and the emerging Neolithic. In the Mediterranean woodland zones of the Levant, populations were mostly sedentary, while in the more arid regions of the Negev, Sinai, and eastern Jordan, populations were more mobile and reliant on hunting5,6. How climate and population dynamics during this crucial period in human history unfolded further south, on the Arabian Peninsula, is poorly understood.

The presence of human populations in northern Arabia has been primarily linked with episodic humid phases10,11. Evidence from palaeolake deposits and associated pollen and molluscs indicate increased rainfall and vegetation during the Holocene humid period, ~10–6 ka11–16. Several sites document human occupation of the region between 10 and 8 ka, such as in the Umm Jirsan lava tube in the Harrat Khaybar17, and the sites of Al Rabyah12, Jebel Qattar18, and Jebel Oraf19, all located in the Jubbah oasis. Radiocarbon ages from Neolithic sites across north-western Arabia suggest a peak in human activity between 7.6 and 6.8 ka, which corresponds with the end of the Holocene humid period19–23. Neolithic communities built large stone structures, including large hunting traps known as desert kites, and large rectangular ritual structures called mustatils, which stretch up to 620 m in length21,23,24. Pastoral communities also created a rich record of rock art, with thousands of depictions of wild animals such as ibex and livestock such as cattle. These are typically stylised, with human figures being elongated with extremely thin arms, and animal depictions with exaggerated horns25,26.

Prior to the onset of the Holocene humid period, little is known about the relatively arid period spanning the end of the Pleistocene and the earliest Holocene in Arabia. An absence of dated archaeological sites has led to a presumed absence of human occupation of the Arabian interior. However, superimpositions in the rock art record appear to show earlier phases of human activity, prior to the arrival of domesticated livestock25.

In 2022, a rock art site was discovered at Sahout (SAU), an area south of the Nefud desert. Here, sandstone outcrops form low-lying mountain ranges that are separated by scattered sand dunes and rocky pavements (Fig. 1). Survey documented 18 life-sized engravings of camels, ibex, and equids, with stratigraphic analysis suggesting that multiple large camel engravings may predate Neolithic engravings and the Holocene humid period. However, test excavations did not permit a correlation between dated deposits and rock art27. Three further panels with large camels were recently documented by members of the public in localities ca. 25 km further south (Fig. 1). Their coordinates were compiled by the Saudi Heritage Commission and shared with our team. This information provided an opportunity to document additional panels belonging to this possible early Holocene rock art tradition, and to survey and excavate any associated archaeological deposits.

Here we report the results of archaeological surveys and excavations at rock art sites with life-sized camel engravings south of the Nefud desert, as well as analyses of spatially associated playa deposits. Three archaeologically unexplored areas were visited during our fieldwork in 2023: Jebel Arnaan (ARN), Jebel Mleiha (MLH), and Jebel Misma (JMI). The three areas span ~30 km along the southern edge of the Nefud desert (Fig. 1). To acquire paleoenvironmental context for the region, playa sediments were excavated and dated at ARN and JMI (Fig. 1). The primary aim of this research was to test if the rock art panels and archaeological deposits represent earlier occupations during the Holocene humid period, resulting in a condensed chronology of rock art production, or if they belong to earlier periods and represent a longer period of human presence in northern Arabia.

Results
Regional geomorphology and palaeoenvironments
To evaluate the terminal Pleistocene and early Holocene environments of the region, trenches were excavated at four playas in the vicinity of the archaeological sites, two of which contained sufficient sediment for palaeoenvironmental analysis and luminescence dating: ARN (Site 1) and JMI (Site 4), (Fig. 1; Supplementary Note 5 and Supplementary Fig. 42). As local centres of deposition, and areas where water accumulated in the past, these playas provide archives of hydroclimate. Gravels found at the base of both 2 m deep trenches were poorly sorted, containing pebbles of up to 5 cm, and were interpreted as alluvial fan deposits. A luminescence age of 68.8 ± 5.0 ka (MIS-B-1) from JMI indicates that these sediments were deposited at the Marine Isotope Stage 5a to 4 transition (Table 1). Palaeohydrological activation at this time is consistent with both broader regional records28 and a surface find of a Middle Palaeolithic Levallois core from JMI (Supplementary Fig. 32).

At both excavated paleoenvironmental sites, the overlying sediments consist of a thin interval of alternating much finer-grained and well-sorted aeolian sand and playa deposits. These are followed by a prolonged sequence of playa deposits consisting of quartz sand, clays (illite and kaolinite), and calcite, indicating more humid conditions with increased water accumulation in these local depressions. We interpret the onset of playa sediment accretion as representing the change in the balance between aeolian erosion and fluvial sedimentation. During the LGM, the hyper-arid environment meant that any fine-grained sediments deposited in ephemeral floods were subsequently eroded by the wind. As the climate became less arid, fluvial sedimentation increased, becoming greater than the aeolian erosion rate and sediments started to accumulate. However, the subordinate carbonate concentration and the absence of root traces and organic-rich layers suggest that conditions remained too dry for the establishment of more permanent water bodies, indicating that a dryland environment persisted around these ephemeral, and probably seasonal, lakes. Luminescence ages constrain the onset of surface water to between 17.1 ± 1.7 ka (MIS-B-3) and 15.5 ± 1.5 ka (MIS-B-2) at JMI (Site 4) and to 12.7 ± 2.1 ka (SAH-L3-1) at ARN (Site 1) (Table 1). The onset of sedimentation after a long hiatus, coupled with an increase in calcite noted in both sedimentary records, indicates that local conditions gradually became more humidafter ~16 ka at JMI to ~13 ka at ARN, with these site-specific differences in timing likely due to differences in catchment hydrology (Table 1). These sites thus represent the earliest evidence from northern Arabia of increased humidity following the hyper-arid LGM. However, the lakes were ephemeral, indicating an arid or semi-arid climate prevailed in the region.

Monumental rock art
Surveys at ARN and JMI identified previously unknown rock art landscapes with life-sized depictions of wild mammals and human figures, and an individual panel at MLH. Across the three areas 62 rock art panels were recorded, containing 176 engravings. Of these, 130 were life-sized and naturalistic engravings depicting camels (90), ibex (17), equids (15), gazelles (7), and aurochs (1), with individual representations frequently measuring up to 2.5–3.0 m in length and 1.8–2.2 m in height. In addition, we identified 2 camel footprints, 15 smaller scale naturalistic depictions of camels, 19 human figures, 4 human faces or masks, and 6 unidentified, partial engravings (Supplementary Data 1).

Most of the recorded engravings show camels in a detailed and naturalistic style that echoes the reliefs of the Camel Site to the north of the Nefud desert. This includes the frequent depiction of a bulging neckline, indicating they represent male camels in rut29,30 (Fig. 2A, B). The depictions span multiple engraving phases, with images often overlapping on rock surfaces. Sometimes this was done to update an existing representation (Fig. 2B) or to depict a different animal species (Fig. 2C). We distinguish four phases here. Two early rock art phases: small, stylised depictions of women (phase 1, traced in green), followed by large human figures in frontal view (phase 2, traced in yellow). These human figures were always noted to be older than, i.e. underneath, the recorded life-sized animal representations (Fig. 2A), and they make up a much smaller proportion of motifs. The third phase shows detailed, extremely naturalistic representations of animals, where each depiction has individual characteristics (traced in white) (Fig. 2A, B). A later, fourth phase (traced in blue) shows more stylised depictions of animals with cartoonish features, including rounded eyes and horn ridges, and more standardised, near-identical depictions of animals (Figs. 2C, D and 3C).

Unlike the SAU site, where many of the engravings were found inside narrow gaps between boulders27, engravings at ARN and JMI were found on prominent locations on boulders or cliff surfaces, facing into the landscape (Supplementary Figs. 1 and 7). Some of these panels were etched onto cliff surfaces in inaccessible but highly visible locations (Fig. 3). The difficulty in getting to and engraving these rock surfaces, and their enhanced visibility by height were clearly attractive for the engravers. The precarious nature of the engraving process is particularly evident in the largest recorded panel. On the ground, panel JMI18 is today only visible in optimal light conditions for about 1.5 h in the morning, due to its elevated location and the varnish build-up on the engravings. This panel would have been accessed by climbing up a cliff and then engraved while standing on a downward sloping ledge, only ~30–50 cm in width (Fig. 3B). Today the sandstone is too degraded to reach the ledge safely, and the panel was documented using a drone. The friable nature of the substrate and the slope of the narrow ledges suggest the engravers likely risked their lives to create this art. Engraving at closer range would have required them to use direct percussion, while also preventing them from being able to see the complete image. Twenty-three life-sized camels and equids, each with an individual length of ~1.7–2.6 m were engraved on this surface (Fig. 3C), with the engravings stretching ~23 m across two cliff surfaces at a height of 34 m and 39 m (Fig. 3A), giving this rock art a monumental scale.

All recorded rock art panels show a thick coating of dark rock varnish on the natural sandstone surface and inside the engraved lines (Fig. 2), although on some panels this varnish has partially eroded and is now only visible in areas that are less exposed (Fig. 3C and Supplementary Fig. 3C, D). The re-formation of rock varnish following the exposure of the fresh sandstone during the engraving process has been shown to take over 8 ka31,32, and provides a first indication of the antiquity of these images.

The appearance of multiple life-sized animal engravings is impressive today. Freshly engraved against the varnish, the images would have had considerable visual impact. The durability of the images may have facilitated the remembrance of meaning and symbolism across generations of people using these sites. The large naturalistic engravings, therefore, align with the definition of monumentality, which references great size and effort, but also longevity and remembrance within a community33,34.

Archaeological Excavations
Four trenches revealed stratified archaeological deposits. Two were excavated at ARN (ARN3, T1 and T2), and two at JMI (JMI7 and JMI8, Fig. 1), yielding artefacts including over 1200 lithics (Supplementary Note 2), and 16 bone fragments (Supplementary Note 4). Optically stimulated luminescence (OSL) and radiocarbon dating (Supplementary Note 6) samples from the archaeological deposits attest to human occupation during the terminal Pleistocene and earliest Holocene.

In front of panel ARN3, a 2 × 1 m trench (T1) was excavated directly below two life-sized engravings of camels, one superimposed on the other (Fig. 4). Below recently disturbed sediments, the excavation revealed intact archaeological deposits with layer 5 in particular containing dozens of flaked stone artefacts. This layer was sealed by several large sandstone fragments in layer 4 (Fig. 4), likely the result of a colluvial event. In ARN3 T1, the legs of the engraved camels were buried at a depth indicating that they were engraved no later than when layer 4 was deposited (Fig. 4). Layer 5 included a stone tool that may have been used for engraving the rock art (discussed below) (Fig. 4, orange). Two luminescence samples obtained from layer 5, dating to 12.2 ± 1.4 ka, and 12.8 ± 1.1 ka (Table 1), directly date the burial of the artefacts and pecking tool, and provide an indirect date for the engraving above. Analysis of the engraved lines shows that all images were made using a pecking stone. In some engravings, pecked lines were smoothed in a second step (Fig. 4 inset).

A second trench (T2) was excavated at ARN3 1.2 m to the east, beneath two more camel engravings at the other end of the same boulder surface (Supplementary Fig. 11). T2 also revealed layers containing hundreds of lithics (layers 6–8; Supplementary Fig. 13) with three small hearths in layer 7, one of which was radiocarbon dated to 11.44 ± 0.18 ka (cal. BPUGAMS65278, Table 2). Refits from layers 8 and 9 in T2 testify to the high integrity of the archaeological contexts (Supplementary Note 3).

At JMI, two trenches were excavated beneath boulders featuring rock art panels. At JMI7 a 2 × 1 m trench was excavated beneath life-sized engravings of two camels and an equid, which revealed a single layer with high artefact concentrations (layer 4; Supplementary Fig. 16). At JMI8 a 2 × 1 m trench was excavated below a life-sized engraved camel. Here moderate artefact concentrations were interspersed throughout the stratigraphic sequence, with the highest artefact concentration in layer 2, near the surface (Supplementary Fig. 19). A luminescence sample was obtained from layer 6, which provided an age of 12.0 ± 1.8 ka (JMI8-T1-4, Table 1), consistent with the luminescence and 14C ages at ARN.

Artefact Assemblages
The ARN3 excavations revealed a rich assemblage of occupation debris. In T1, 101 lithics were recovered, with over half in layer 5 (Fig. 4), while in T2, 532 lithics were recovered, with over 95% from layers 5–9 (Supplementary Fig. 13). Chert was the main material used, constituting 36% of the pieces, with obsidian and crystal quartz making up another 23% and 15% respectively (Supplementary Data 2). Lithics showed a diversity of reduction strategies, including small bipolar cores occurring alongside chert bladelets/blades with lamellar scar patterns and often ground platforms (Supplementary Note 3.1).

A total of 30 retouched pieces were recovered. Among these, notches were common with eight notched pieces and two opposed notch blades (Supplementary Table 1). Two chert drills were recovered in T2, as well as a single end scraper from the disturbed upper part of T1. The largest retouched artefacts were two tongue-shaped scrapers from T2 layer 8 (Supplementary Fig. 28). T2 produced seven marginally retouched convergent points made on chert bladelets, while the tanged butt of a point on an obsidian blade was recovered from T1 (Supplementary Figs. 25 and 26). The most distinctive artefacts were a single crystal quartz Helwan bladelet from T1 layer 4 (Fig. 5B), and three chert El Khiam points, a broken butt from T1 layer 5, and both a broken butt and a complete El Khiam point from T2 layer 5 (Fig. 5A and Supplementary Fig. 26). The luminescence age of 12.2 ± 1.4 ka (ARN-T1-2, Table 1) in T1 and the radiocarbon date of 11.44 ± 0.18 ka (UGAMS65278, Table 2) from T2 correspond with the age of El Khiam points from the Levant and therefore indicate that the main occupation was contemporary with the PPNA.

Excavations at JMI7 produced 100 lithics while JMI8 produced 519 (Supplementary Figs. 16 and 19). Quartz was the most commonly used material comprising 65% of pieces, with an additional 20% made from silcrete (Supplementary Data 3). The single core was a silcrete naviform piece from layer 4 in JMI7 (Supplementary Fig. 29). The JMI7 and JMI8 excavations produced nine retouched artefacts (Supplementary Table 2). An opposed-notch chert blade was recovered in layer 5 (Supplementary Fig. 31), with two other chert notched blades recovered from JMI8 layer 4, but these did not have the distinctive opposing notches. This same layer also produced a chert drill with a distal break. A broken Helwan point was found on the surface between JMI7 and JMI8 (Supplementary Fig. 30).

Several of the recovered artefacts have associations with the PPN and even the Natufian in the Levant. Helwan bladelets (Fig. 5B) and opposed notch blades are known from Natufian sites; El Khiam points (Fig. 5A) are an artefact type characteristic of the PPNA, whereas Helwan points and naviform cores are typical for the PPNB (Supplementary Note 3). These artefact types accord with the chronometric dating at ARN and JMI (Tables 1 and 2).

Four grinding stones were recovered from the ARN3 excavations and six from the JMI excavations, along with a facetted stone ball (Supplementary Fig. 34) and two stone platters in JMI7 layer 4 (Supplementary Fig. 35). Two mortars were documented on an exposed rock surface between JMI7 and JMI8 (Supplementary Fig. 33). Mortars are typical of the PPNA35 and have not previously been documented among grindstone assemblages of Neolithic northern Arabia36.

A total of five ground stone beads were recovered, four green pieces from ARN T2 layers 7 and 9, and one from JMI8 layer 2. The recovery of two broken beads and one unfinished bead, together with drills at both sites, suggests on-site manufacture. Two marine dentalium (tooth-shell) beads were recovered from ARN3 T2, layers 7 and 8 (Fig. 5F and Supplementary Fig. 41). Among mostly red pigment, noteworthy was a crayon of green copper ore pigment from ARN3 T2 layer 7. Green pigment and ground stone beads are characteristic of the earlier PPN37,38. Dentalium shells are known from the PPNA39 and had to be collected from the Mediterranean Sea or the Red Sea, making the latter the closest potential source at over 320 km away.

Three tools with clear battering marks were recovered from directly below engraved panels. One is from a stratified and dated archaeological context underneath a life-sized camel engraving at ARN3 T1 (Figs. 4 and 6), immediately below OSL sample ARN-T1-2, dated to 12.2 ± 1.4 ka, and above sample ARN-T1-3 dated 12.8 ± 1.1 ka (Table 1). Two additional tools were recovered on the surface beneath panels ARN30 and JMI8 (Supplementary Fig. 37). The ARN tools are made on clasts of ferruginous sandstone, a tough material not immediately available at the rock art localities, while the JMI8 tool is made of silcrete, a material available at SAU. The tools are all wedge shaped, and the two made on ferruginous sandstone were flaked to sharpen the pecking edge. The tools comfortably fit into a medium-sized adult hand, with the battered edges protruding (Fig. 6B, C). Battering is evident on multiple edges of all three tools, indicating they were used extensively. Due to their angular form, the tools are not viable as lithic hammerstones in the arced free-hand percussion motion; however, the tapered ends would make good surfaces for the direct end-on percussion required to peck petroglyphs (Supplementary Note 3.3). The tool recovered from ARN3 T1 was used to peck and could thus have been involved in the production of either of the two camel engravings above (Fig. 4). In Arabia, this type of tool was first noted at the Camel Site, where traceological analysis on silcrete pieces showed damage consistent with sandstone engraving40. Comparable tools and patterns of wear have also been observed at petroglyph sites in Europe41 and South America42,43.

Methods
Permits and permissions
Permission for excavations in Saudi Arabia, sampling, export of samples and artefacts to the United Kingdom, and analysis was granted by the Heritage Commission, Ministry of Culture, Saudi Arabia.

Rock art
Rock art panels were recorded using pro-forma record sheets, with content, size and GPS location noted, and documented using high-resolution digital photographs as raw files and JPGs. To enhance faded details on the rock art, some photos were enhanced using Adobe Lightroom. Key panels were photographed systematically to allow generation of high-resolution 3D models and orthophotos using Metashape photogrammetry software. One exceptionally large panel was located on a cliff 34–39 m above the ground (Fig. 3C) and had to be documented using a DJI Mavic Mini 2 UAV due to its height and inaccessibility, with the resulting photographs combined into an orthophoto to facilitate analysis.

Rock art surveys were carried out systematically, with survey teams following the base of jebels and exploring all boulders and rock surfaces along the base and within heights that could safely be reached. At Jebel Arnaan, rock art survey followed a gully that leads up the mountain slope and connects to a wadi above (Fig. 8B).

A total of 106 rock art panels were documented across all three regions (Jebel Arnaan, Jebel Mleiha and Jebel Misma). Distinct surfaces of boulders were defined as separate panels, with multiple surfaces on the same boulder labelled with the same number, distinguished by a letter suffix (e.g. ARN3_A, ARN3_B).

Excavations
All trenches were hand-dug by trowel using the single context method55. Thicker deposits were sometimes divided into multiple contexts for extra stratigraphic control. Contexts were recorded using project-specific proforma record sheets. Depths were recorded with a line level, with five points taken for each context. Excavated sediment was sieved through a 3 mm mesh with all artefacts and faunal remains retained. The position of key finds was manually measured using a plumb bob from an origin in one corner of each trench.

Artefacts
All lithics were classified by material, counted, and weighed. Any retouched pieces and cores were assigned to types. Key types were photographed and measured. Grinding stones were assigned to types, their ground surface form characterised, and any complete dimensions measured. Pigment was weighed and pieces with striations visible at low magnifications designated as crayons. Bead diameter, aperture width, and thickness were measured.

Luminescence dating
Luminescence dates presented in this study were determined using optically stimulated luminescence techniques applied to quartz. These measure the time elapsed since sediments were last exposed to sunlight. Opaque metal tubes were hammered into cleaned sections, transported to the UK and analysed as described in Supplementary Note 6.1. Environmental dose rates were calculated using location and overburden density (cosmic rays), field gamma spectrometry (gamma), and thick-source beta counting (beta). Luminescence analyses were carried out by Simon Armitage at the School of Life Sciences and the Environment, Royal Holloway University of London, United Kingdom.

Radiocarbon dating
Samples suitable for radiocarbon dating were collected from stratified archaeological deposits during excavation and included charcoal-rich sediment samples from hearth deposits, ostrich egg shell, micro charcoal, and one piece of shell. The latter was identified as a pearl oyster (Supplementary Note 4). Samples for radiocarbon dating were sent to the Centre for Applied Isotope Studies (CAIS) at the University of Georgia and analysed as described in Supplementary Note 6.2.

Palaeoenvironment
Trenches were dug in the middle of the playa settings, up to 2 m deep. These sections were described sedimentologically and sampled for geochemical lab analysis and luminescence dating. The XRD semi-quantitative analysis of the major mineral components was carried out using a D8 Bruker machine, at the laboratory in KAUST, with a chosen angle (2θ) between the incoming and outcoming X-ray beam between 5 and 80°. The mineral phase interpretation was done using DIFFRAC.EVA software and the results are presented as a proportional percentage of the mineral phase present in the analysed samples (Supplementary Note 5). The samples were powdered using a handheld mortar.

Reporting summary
Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.

Data availability
All data used in this study are available in the Supplementary Information files. All data used to support our results were generated in our research. Sediment samples from playa deposits are stored at King Abdullah University for Science and Technology, Physical Science and Engineering Division. Artefacts recovered during excavations will be returned to and stored by the Heritage Commission, Ministry of Culture, Saudi Arabia, in 2025. Access can be negotiated with the Heritage Commission (faljibrin@moc.gov.sa).

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "With their paper „Monumental rock art illustrates that humans thrived in the Arabian Desert during the Pleistocene-Holocene transition“, Guagnin and colleagues provide data on rock art, paleoenvironment and archaeology of the terminal Pleistocene to earliest Holocene period from northern Saudi Arabia. In a spatial extension of their previous study Guagnin et al. (2023, Archaeological Research in Asia 36) they demonstrate here the presence of life-size camel engravings and archaeological records broadly similar to their previous findings about 15 km to the north. However, the authors state here that: “For the first time, secure stratigraphic contexts from excavations directly beneath the rock art panels allow these engravings to be dated.” (page 4 main ms, 2nd pragraph).\nIn general, the results presented are interesting. However, I argue below that only the archaeological results provide somewhat solid data for publication. The arguments and data that the authors present with regard to the dating of rock art and their reconstruction of palaeoenvironmental conditions, in contrast, are in my opinion not supported by the presented data. I detail my concerns below. Since they are substantial, I will not go into the details of the minor issues.\nIn its current state, I cannot recommend publishing this manuscript in Nature Communications.\nOne of the main topics in this paper is the age of the life-sized camel engravings. It is always a challenge to date engravings and having sediment deposits partially covering these is one of the more promising options to get a minimum age. The authors present one example of such a context (trench 1 in their ARN3 area). Here they link OSL ages from layer 5, about 40-50 cm below the camel engraving with the engraving. This excavated layer has multiple lithic artifacts and in particular one engraving tool could be found in that layer. I understand that the authors would like to see a link between engraving and engraving tool given the spatial proximity, but from a strictly scientific and stratigraphic perspective this conclusion is not supported by the data (see figure 3). There is no stratigraphic connection between the dated OSL samples and the engraving. The only possible conclusion is that these engravings are younger than the age estimations of layer 5. Whether this is a couple of years, a few decades or millennia, remains speculative.\nConsidering rock art, I noted that the camel shown in grey in figure 3 has its hump very far back. To me this does not look like a normal dromedary that one would expect as part of the local wild fauna. I was wondering if this could then be a Bactrian camel with two humps or an interbreed between dromedary and Bactrian (in Arabia called “bukht”)? Bactrian camels did not occur in Arabia naturally and were only imported during the Iron Age. The authors should provide additional information on the camel species and should consult an expert for camels. I further noted that the lower parts of the legs in figure 3 are shown with dashed lines. What does that indicate? Were the engravings incomplete here? This also needs to be clarified since this is important when assessing the spatial relationship between engraving, the sand deposits and the OSL sample locations.\nThe archaeology and its age estimations on the other hand are comprehensible and well demonstrated. Although for the presentation of new archaeological material I miss a detailed description of how the excavations have been conducted. Did the authors sieve for example? How did they remove the sediment, all area at once or did they subdivide the excavated area as it would be a modern standard procedure? How did they document the position of the finds within the excavated layer? In Suppl. Fig. 11 there is no obvious instrument that would allow measuring the position of the findings, so how have the authors done the documentation? Moreover, what does for example “layer 5 (context 006)” as mentioned in the suppl mean? What is the context in this case? The counts on lithics provided, what do they include? How many lithic artifacts larger than 2 cm did the authors document and how is their horizontal distribution? Please avoid expressions such as “many” or the “majority” when presenting numerical data. Provide numbers instead to allow the reader to follow your presentation. So, while I consider the archaeology relevant, the presentation of the archaeological excavations and findings require significant revision following my questions above.\nSince I am not a specialist, I cannot comment on the presented chronometric dating results and related methods.\nBeside my concerns regarding the age of the engravings, the other major issue is the scarcity of convincing evidence provided by the authors for the claim of “more humid conditions with increased water accumulation” (page 6 of the main manuscript) demonstrated by the “prolonged sequence of playa deposits” (ibid). Playa deposits is a flexible term that I think needs to be defined. Given table 1 and the grain sizes listed there, all but one context is composed of fine sand, which might be washed or blown in. In my understanding this is not the classic type of sediment that forms exclusively in standing water bodies. I think the reader would much appreciate it if the authors would define what they consider to be playa deposits exactly and how they differentiate between different depositional conditions.\nReading through their description of the palaeoenvironment results left me somewhat confused since there are contradictory statements. On the one hand they say: “[…] subordinate carbonate concentration, and the absence of root traces and organic-rich layers suggests that conditions remained too dry for the establishment of more permanent water bodies, indicating that a dryland environment persisted […]” (page 6 of the main ms). While only a few sentences later they say: “These sites thus represent the earliest evidence from northern Arabia of increased humidity following the hyper arid LGM. However, the lakes were ephemeral, indicating an arid or semi-arid climate prevailed in the region.” (page 7, main ms). So what is the author’s final conclusion? To me the presented data clearly speaks in favor of a continuity of arid conditions with infrequent rain events that led to the formation of some shallow puddles, which have existed for a few days. A phenomenon that can also be observed today in Arabia and other deserts after rain. If there is no further supporting evidence for a longer duration of water bodies from these sections, such as the presence of pointer species for lacustrine conditions, these deposits can in my view not be cited as evidence for increased humidity.\nTo wrap up, I think the presented conclusions for “securely dated rock art” and “the earliest evidence for increased humidity from northern Arabia” are not supported by the presented data. While saying this, the presented archaeological data is, although not comprehensively presented, at least convincing with regard to the chronology and cultural context of the population settled here at some time between 13.8 ka and 10.9 ka ago. That the authors can link this presence to Levantine Khiamian tradition is very interesting and would be worth further exploration. The excavations are relatively small since I suppose they have been started initially to collect chronometric data for the rock art. It might be worth going back, open larger trenches and see what the groups carrying Khiamian traditions else have left in the deep desert. The 500+ artifacts (if not 490 were smaller than 5 mm, please clarify the frequency of artifacts larger than 2 cm) could hint at an archaeological record of decent size. Finally I would like to point out that the dating of the Khiamian material from this site is relatively early compared to the standard time range proposed for the Levantine sites. Again an interesting detail that could be further explored.", "reviewer_2": "In this article, the collaborating authors draw upon multiple strands of archaeological and paleoecological evidence to reconstruct a late Pleistocene-Early Holocene environment and populate it with fauna and human groups. For the latter, the archaeological evidence offers chronological and some cultural details such as technical affinities with northern traditions and long-distance exchanges of exotic materials. Mobility of these human groups is implicit, by virtue of the seasonal availability of local resources and potentially by depictions of seasonal characteristics of fauna. A major focus of this paper is the local rock art, studied in three newly reported locations and linked to well-reported rock art studies across a broader region of northern Arabia. While rock art is rich in imagery and clues to the symbolism and communications of its creators, it is rarely possible to date it or to link rock art unequivocally to other details of the archaeological record. The significance of this paper lies in the assertion that the earliest phase of this reported rock art can be securely assigned to the Late Pleistocene-Early Holocene transition and that the reported artifacts show an expansion of people into formerly hyper-arid zones after the Pleistocene LGM abandonment. This argument supposes that rock art of Phase 1 serves as a marker of human activity earlier than previously documented Late Pleistocene-Early Holocene Arabia.\nThere are two key strands to this argument for which the authors supply details and which this reviewer is best qualified to assess. (Paleoecological details of sediment characteristics and dating methods underpinning the regional environmental reconstructions, including paleolacs, are not my forte). One strand is the age of the rock art and its indirect dating through purported association with artifacts. The second strand is the absence of evidence for Late Pleistocene and Epipaleolithic occupation and use of local resources to purport a re-population/expansion, driven by exogenous climatic factors) into a region previously lacking human occupation. This second strand is the major justification for publication in Nature Communications, even as the evidence and topic of rock art is intrinsically interesting, if localized. Similar and intrinsically localized evidence can be of the highest scientific interest, as studies of 40,000-year-old cave paintings in Southwest Sulawesi have demonstrated.\nTo examine these arguments, therefore, some close consideration of the linkages and chronologies of rock art and excavations is warranted. While the evidence is well presented, very well illustrated, clearly organized, and amply supplemented with extensive online supplemental materials, there remain some ambiguities. It is fortuitous to find sediments sealing or obscuring rock art as was the case at site ARN3 T1. This is the only fully reliable stratigraphic dating (indirect) for rock art.\nA critical item therefore is the white camel (phase 1) on the panel ARN 3 with its legs covered in sediment. The authors assign this to the Pre-Pottery Neolithic (layer 5 in ARN T1). With a rockfall (layer 4) overlying layer 5, the camel engraving (and all phase 1 rock art classed as contemporaneous with it by the authors) could be later than layer 5, engraved independently and sealed at a later date by rockfall. While the evidence is strongly suggestive of a PPNA (not Natufian) association with layer 5 and therefore of the rock art “engraving” of a camel, questions remain. The tool argued to be used for engraving is also described as a “pecking stone” (Supplement 3.3 p. 16-170, and this pecking motion is also described in Supplement 3.4 p. 42 (Figure 37 on p. 44). I would like to see clarification of\nA) The reasons for dating to Natufian (a few notched flakes and mortars) instead of PPNA (later, consistent with and unremarkable for other finds in Arabia, e.g., Jebel Oraf). Note another “pecking” tool recovered on the surface at ARN30 (rock art production method not specified in Supplementary Table 1). Radiocarbon dates are consistent with PPNA, not Natufian—unless one reads the most ancient extent of the radiocarbon determination rather than its median.\nB) The difference between engraving and pecking and the reasoning for a pecking tool to be an engraving instrument. This is critical for the association of the tool in ARN3 T1 and the camel engraving above it. I suggest more text on how the rock art was produced (pecking, engraving, other?) and explanation whether production criteria was included in the analysis of phases/chronology—or do different production techniques cross-cut the chronological assignments of phases? I also suggest (in light of the access challenges) that authors address whether one or many people were needed and consider the person hours of labor involved. These considerations may lead to further insights on group size, frequency of passage, and community dynamics.\nC) The reason the camel engraving cannot be later than layer 5, that is, PPNA occupants at layer 5. As I read their evidence, it is plausible that there is a abandonment layer, then layer 4, which covers the camel engraving of rock art phase 1). It is possible that the camel engraving postdates layer 5 (by an unspecified period of time) and pre-dates layer 4 collapse (documented by authors in section Figure ). It would seem that a post PPNA composition of phase 1 would be very much consistent with evidence elsewhere of PPNB cultural influences among populations in the north Arabian humid period.\nNote that if the evidence is stronger (as I read it to be) for PPNA not Natufian incursions into the arid zone, the chronological assertions are less remarkable than the authors indicate, or they could be re-stated for local versus peninsular significance. (See Crassard et al. 2013, cf., Hilbert et al. 2014 both cited by authors). Even so, the analysis classifying different episodes of rock art based on stylistic grounds and overlap/superposition of images is new and potentially foundational in the region.\nThe second strand is the absence of evidence for Late Pleistocene and Epipaleolithic occupation (at this locale) and use of local resources to purport a re-population/expansion, driven by exogenous climatic factors. The authors need to broaden the significance of this paper beyond the repopulation of this specific locale in the Arabian Peninsula. This might be done by referencing other and adjacent geographies: the greening of the Sahara or the LGM refugium in the Arabian/Persian Gulf theory come to mind.\nA few minor points:\nCaption in Figure 1 (main text) documents 131 rock art images, versus (in text) account of 176 images (line 150).\nLine 234—dating the engraving of the camel by the height of its legs. Even if the authors’ reasoning is sound (? See above), this line is confusing and needs to be clearer for first reading.\nLine 297 and ff. lithics—Supplement p. 36 & Fig 20—that there is a transition in materials between PPNA and PPNB layers is interesting and deserves greater comment. A gap in time? Different populations? Different economic pathways for the circulation of goods?\nLine 379 argues that engravings reflect a rainy season. I tend more to agree with the multiple and sometime symbolic/ideological and/or social communications the authors explore in discussion. It is altogether too easy to “read” as economic and functional-historical images one doesn’t access through cultural practice and initiation. I’d prefer to keep the interpretation open and refrain from linking specifically to moisture/rainy season.\nSupplementary Figure 10 has a dark shadow that obscures critical section information. The authors would be forgiven for photoshop manipulation of this figure to illuminate any section details that can be discerned.\nLikewise it is odd that the authors elected not to excavate fully adjacent/perpendicular to the limestone face bearing the rock art (as they did in ARN3 T2). If this was done subsequent to the image, a description of the lowest extent of phase 1 camel engraving (outlined in black) would be warranted.\nMissing references include other efforts at dating rock art in Arabia, either through indirect association with sediments (Rachad and Inizan’s work at Sa’ada, Yemen) or through stylistic classifications and their superposition in different panels (also used in this manuscript) (e.g., Philby-Ryckmans’ expedition publications). Direct dating has recently been possible with (organic) painting (Rowe et al. The Holocene 2022).", "reviewer_3": "A very interesting piece of work. It is good to see the archaeology tied to the rock art, together with the various dating methods. A few remarks:\nLine 93 What stone are the carvings on (I assume sandstone, but please state at the outset)\nLine 160 (Fig. 1) A: Map could be larger and B possibly two gazelle and one goat\nLine 205 Freshly engraved INSERT COMMA the images…\nLine 366 omit comma\nLine 374 could the aurochs not be a record of what has been seen elsewhere?\nIn the paragraph starting on l. 431 maybe add something about representation of the animals also being a record of the environment, potentially sympathetic magic, territorial markers, indications of herd movements (an extension of the statement about routes l. 437),\nLine 489 the monumental rock art in Arabia sets them apart from the Levantines—maybe a phrase to explain what sort of rock art was found in most of the Levant… Also, maybe worth noting that such monumental rock art is found in North Africa, though not in Egypt. And, it might be worthwhile speculating (if possible) why monumental images were so common here.\nWhat animal bones were recovered from the area? Can these be linked to the rock art?", "reviewer_4": "The manuscript entitled: “Monumental rock art illustrates that humans thrived in the Arabian Desert during the Pleistocene-Holocene transition” presents highly original data from a key archaeological site in Northern Arabia. With regard to the interdisciplinary scope and the relevance of the topic presented in the Ms I have no doubt that this manuscript is a potential very good fit for Nature Communications as it is relevant for the broader scientific community. Also, with regard to the highly original multi-method dataset this Ms deserves publication in a high-ranking outlet. However, I was a bit less impressed with the structure and conciseness of the main manuscript. The manuscripts is occasionally redundant and the argumentation is – at least party – not convincingly structured. Even more importantly it is oftentimes difficult to trace back the scientific evidence that should support the argument/interpretation. Also, some of the figures need to be improved especially with regard to their self-explanatory power. From my perspective it is crucially important that the actual scientific evidence is directly associable with the corresponding figure (especially Fig. 6) or interpretation. In summary, I see the high potential of the paper and I am convinced that it can have a significant scientific impact, however, a major revision is required to make it fit for publication. Below I provide some feedback that will hopefully help to make the Ms more concise. With regard to the supplement, I focused on the geomorphological (note 5) and the luminescence data (note 6) and provide some additional feedback especially with regard to documentation and interpretation.\n- please find detailed feedbak in the reviewer attachement."}, "author_response": "We thank the reviewers for the time they have taken to review our manuscript. We\nappreciate their detailed comments, which have helped us clarify and strengthen our\nmanuscript. We have addressed all comments (see below, in blue) and have made\nextensive changes to the text and figure captions, we have included six new references,\nprovided an additional figure, and changed four figures in the manuscript. The\nSupplementary Information is now 587 words longer and we have added 1 new figure.\nReviewer #1 (Remarks to the Author):\nWith their paper „Monumental rock art illustrates that humans thrived in the Arabian\nDesert during the Pleistocene-Holocene transition“, Guagnin and colleagues provide\ndata on rock art, paleoenvironment and archaeology of the terminal Pleistocene to\nearliest Holocene period from northern Saudi Arabia. In a spatial extension of their\nprevious study Guagnin et al. (2023, Archaeological Research in Asia 36) they\ndemonstrate here the presence of life-size camel engravings and archaeological records\nbroadly similar to their previous findings about 15 km to the north. However, the authors\nstate here that: “For the first time, secure stratigraphic contexts from excavations directly\nbeneath the rock art panels allow these engravings to be dated.” (page 4 main ms, 2nd\npragraph).\nThe previous study mentioned by the reviewer consisted of 2 extremely small test\nexcavations (80cmx80cm and 20cmx20cm, to a depth of 12 cm). This scant material only\nproduced a single 14C predating the Neolithic, and did not provide any data to date\nrock art. These test excavations were conducted near rock art but not in a location\ndirectly associated with rock art (i.e. not directly below an engraved panel – as is the case\nin the present study at Jebel Arnaan). All we were able to say in this previous paper was\nthat the rock art seems to mirror the occupation sequence and “may have begun earlier\nthan previously thought” and that there was “broader geographical extent to human\noccupations prior to the Holocene humid period” (Guagnin et al., 2023). We reference\nthis data throughout the manuscript.\nWe have added a sentence “However, the limited excavations did not permit a\ncorrelation between dated deposits and rock art.” To state this difference more\nclearly.\nIn general, the results presented are interesting. However, I argue below that only the\narchaeological results provide somewhat solid data for publication. The arguments and\ndata that the authors present with regard to the dating of rock art and their\nreconstruction of palaeoenvironmental conditions, in contrast, are in my opinion not\nsupported by the presented data. I detail my concerns below. Since they are substantial, I\nwill not go into the details of the minor issues.\ncontext, particularly on rock art dating and on the formation of rock varnish. We have\nnow integrated this information and thank the reviewer for alerting us to these gaps.\nOne of the main topics in this paper is the age of the life-sized camel engravings. It is\nalways a challenge to date engravings and having sediment deposits partially covering\nthese is one of the more promising options to get a minimum age. The authors present\none example of such a context (trench 1 in their ARN3 area). Here they link OSL ages\nfrom layer 5, about 40-50 cm below the camel engraving with the engraving. This\nexcavated layer has multiple lithic artifacts and in particular one engraving tool could be\nfound in that layer. I understand that the authors would like to see a link between\nengraving and engraving tool given the spatial proximity, but from a strictly scientific\nand stratigraphic perspective this conclusion is not supported by the data (see figure 3).\nThere is no stratigraphic connection between the dated OSL samples and the engraving.\nThe only possible conclusion is that these engravings are younger than the age\nestimations of layer 5. Whether this is a couple of years, a few decades or millennia,\nremains speculative.\nSince engravings are produced on surfaces that are clear of sediment, the level of\nsediment at the time of the creation of the rock art has to be below the image. Unlike\nartefacts which are deposited alongside sediment, only sediment that accumulates after\nthe engraving event will end up covering rock art images. If we were to rely on the\nmethod the reviewer suggests for dating the rock art of dating covering sediment, we\nwould have an artificially short and young chronology for the art. We disagree with the\nview that a tool used to produce rock art cannot be used as evidence for the age of rock\nart - we are interested in dating the creation of the rock art rather than its burial, which\nas the reviewer says will have happened an unspecified amount of later.\nThe petroglyphs were necessarily made with stone, and since stone does not decay, we\nshould expect to find some of these tools in spatial association with these large\nengravings. Our analyses match previous research by Hilbert et al. (2022), that has shown\nthat the tools used to engrave sandstone are often left directly below the engraved\npanels. The shape of the tool and the battering marks show that it could not have been\nused for any other stone-working task. There is no likely scenario in which a tool that\nwas used to peck sandstone could have ended up in a sealed archaeological context\ndirectly below an engraved panel but not been used to make this rock art. There is no\nother rock art within a distance of 200 m from the location of the pecking stone (all rock\nart on this boulder is phase 3 and 4 – shown in the new Figures 2C and 4). The only\nreasonable assumption in this case is that the tool was used to produce one of the two\nengravings above.\nOur research focusses on the stratigraphic connection between the OSL samples and the\nengraving tool (pecking stone). Previous research at the Camel Site has also shown that\nlarge, naturalistic representations of Camels are Neolithic or older (Guagnin et al., 2021),\nbased on results from OSL dating beneath fallen boulders and XRF analysis of rock\nvarnish (Guagnin et al., 2021; see also Andreae et al., 2020; Macholdt et al., 2018;\nprecise date by having discovered an engraving tool in a stratified context rather than\nlying on the surface, and that we have found engravings on a much larger scale – they\nare not limited to a confined area but spread along routes in the landscape.\nConsidering rock art, I noted that the camel shown in grey in figure 3 has its hump very\nfar back. To me this does not look like a normal dromedary that one would expect as\npart of the local wild fauna. I was wondering if this could then be a Bactrian camel with\ntwo humps or an interbreed between dromedary and Bactrian (in Arabia called “bukht”)?\nBactrian camels did not occur in Arabia naturally and were only imported during the Iron\nAge. The authors should provide additional information on the camel species and should\nconsult an expert for camels. I further noted that the lower parts of the legs in figure 3\nare shown with dashed lines. What does that indicate? Were the engravings incomplete\nhere? This also needs to be clarified since this is important when assessing the spatial\nrelationship between engraving, the sand deposits and the OSL sample locations.\nWe agree that the hump is very far back. We think the camel is actually shown in the\nprocess of getting up from a sitting position – and we do have some engravings of\nsitting camels in our dataset. The hindlegs of this camel have not been preserved, so we\ncannot prove this interpretation and have thus not included it in the manuscript. We also\nknow of several “failed” engravings, where lines were placed in the wrong position, and\ncorrected in a later engraving. In our previous paper we show a panel where the lines of\na hump were corrected, and then superimposed with a new engraving of a camel that is\napparently also in the process of standing up (Guagnin et al., 2023: 2B). We agree with\nthe reviewer that the depiction of these details merit further analysis, but this is beyond\nthe scope of this current manuscript.\nSaudi Arabia has indeed got some very early representations of hybrid camels, but these\nanimals were only introduced at the end of the 2nd or beginning of the 1st millennium BC.\nThese engravings are generally associated with inscriptions, and follow the very different\nstylistic conventions of Iron Age rock art (they are small, only ca 20cm high, and lack\ndetail – except the characteristic double hump). Crucially, the weathering and varnish\nbuild up preserved on some of the better preserved panels in our study has been shown\nto take at least 8000 years to form (Andreae et al., 2020; Macholdt et al., 2018). This\ndifference is so pronounced that it is clearly distinguishable with the naked eye. It is\ntherefore not possible that any of the representations show domesticated or “interbred”\ncamels.\nWe have added extensive information and data on rock varnish throughout the\nmanuscript:\n We have added a paragraph on rock varnish formation in the “Monumental rock\nart” section, as well as references to relevant research in Arabia and in the Sahara.\n We have also referenced figures that show this varnish in the manuscript and\nSupplementary Information.\n3\n We have added a detailed photo of the engraved lines to the new Figure 4,\nwhich shows the engraving technique on panel ARN3 and also small areas where\ndesert varnish has survived the extensive erosion evident on this panel.\n We have added a sentence on rock varnish in the discussion and referenced key\npublications.\nThe lower parts of the legs are shown with dashed lines to indicate they were covered in\nsediment. We have clarified this in the caption.\nThe archaeology and its age estimations on the other hand are comprehensible and well\ndemonstrated. Although for the presentation of new archaeological material I miss a\ndetailed description of how the excavations have been conducted. Did the authors sieve\nfor example? How did they remove the sediment, all area at once or did they subdivide\nthe excavated area as it would be a modern standard procedure? How did they\ndocument the position of the finds within the excavated layer? In Suppl. Fig. 11 there is\nno obvious instrument that would allow measuring the position of the findings, so how\nhave the authors done the documentation? Moreover, what does for example “layer 5\n(context 006)” as mentioned in the suppl mean? What is the context in this case?\nWe state in the methods section that trenches were excavated using the single context\nmethod. We now provide a reference for this method for clarification. We state that all\nsediment was sieved through a 3mm sieve and that trenches were hand dug using a\ntrowel. Areas were not subdivided as our trenches were comparatively small at either\n2x1m or 1x1m. The positions of finds were manually measured from an origin in one\ncorner of each trench using a line-level and plumb bob. Excavations were carried out in\nMay of 2023, with the use of technical equipment limited by the extreme heat and\nunnecessary in small-scale excavations. We have now included a description of our\nmeasurements in the methods section.\nOur supplementary material noted the context number from excavations alongside the\nlayer number with the intention of providing more clarity and easier cross-referencing\nwith excavation notes. We realise this may have been unintentionally confusing to the\nreader. We have removed the context numbers throughout the SI document for clarity.\nThe counts on lithics provided, what do they include? How many lithic artifacts larger\nthan 2 cm did the authors document and how is their horizontal distribution? Please\navoid expressions such as “many” or the “majority” when presenting numerical data.\nProvide numbers instead to allow the reader to follow your presentation. So, while I\nconsider the archaeology relevant, the presentation of the archaeological excavations\nand findings require significant revision following my questions above.\nAll lithics recovered during excavation are included in the analysis, we specify this in the\nmethods. We do not use size cut-offs as this biases lithic analyses, particularly in the case\nof microlithic assemblages such as these. We have now added a figure (Supplementary\nFigure 14) showing the horizontal bedding of the lithics in ARN3 T2. We have deleted the\n4\nsingle use of the word majority from the main text and the three uses of the word many\nfrom the supplementary.\nBeside my concerns regarding the age of the engravings, the other major issue is the\nscarcity of convincing evidence provided by the authors for the claim of “more humid\nconditions with increased water accumulation” (page 6 of the main manuscript)\ndemonstrated by the “prolonged sequence of playa deposits” (ibid). Playa deposits is a\nflexible term that I think needs to be defined. Given table 1 and the grain sizes listed\nthere, all but one context is composed of fine sand, which might be washed or blown in.\nIn my understanding this is not the classic type of sediment that forms exclusively in\nstanding water bodies. I think the reader would much appreciate it if the authors would\ndefine what they consider to be playa deposits exactly and how they differentiate\nbetween different depositional conditions.\nReading through their description of the palaeoenvironment results left me somewhat\nconfused since there are contradictory statements. On the one hand they say: “[…] \nsubordinate carbonate concentration, and the absence of root traces and organic-rich\nlayers suggests that conditions remained too dry for the establishment of more\npermanent water bodies, indicating that a dryland environment persisted […]” (page 6 of\nthe main ms). While only a few sentences later they say: “These sites thus represent the\nearliest evidence from northern Arabia of increased humidity following the hyper arid\nLGM. However, the lakes were ephemeral, indicating an arid or semi-arid climate\nprevailed in the region.” (page 7, main ms). So what is the author’s final conclusion?\nTo me the presented data clearly speaks in favor of a continuity of arid conditions with\ninfrequent rain events that led to the formation of some shallow puddles, which have\nexisted for a few days. A phenomenon that can also be observed today in Arabia and\nother deserts after rain. If there is no further supporting evidence for a longer duration\nof water bodies from these sections, such as the presence of pointer species for\nlacustrine conditions, these deposits can in my view not be cited as evidence for\nincreased humidity.\nWe clearly state that these landscapes were arid with seasonal lakes (see Abstract) and\nthat arid or semi-arid climate prevailed (see Regional Geomorphology and\nPalaeoenvironments). Conditions were more humid than the hyper arid conditions of the\nLGM – which is also the case for today’s climate. We also clearly state they were not\nhumid enough for the establishment of more permanent water bodies – i.e. less humid\nthan the Holocene humid period. We see no contradiction. Our intention was to\nhighlight that this environment was indeed still extremely arid, with apparently just\nenough seasonal water to allow people to survive.\nWe have changed the wording from “increasingly humid” to “gradually more humid” to\nclarify we talk about an increase in humidity, not “humid conditions”. We have also\nadded three sentences to show how these changes in climate would have changed the\nbalance between erosion and sedimentation by changing from an environment\ndominated by aeolian erosion in the LGM to one subsequently dominated by fluvial\nsedimentation which often includes fine sand.\nearliest evidence for increased humidity from northern Arabia” are not supported by the\npresented data. While saying this, the presented archaeological data is, although not\ncomprehensively presented, at least convincing with regard to the chronology and\ncultural context of the population settled here at some time between 13.8 ka and 10.9 ka\nago. That the authors can link this presence to Levantine Khiamian tradition is very\ninteresting and would be worth further exploration. The excavations are relatively small\nsince I suppose they have been started initially to collect chronometric data for the rock\nart. It might be worth going back, open larger trenches and see what the groups carrying\nKhiamian traditions else have left in the deep desert. The 500+ artifacts (if not 490 were\nsmaller than 5 mm, please clarify the frequency of artifacts larger than 2 cm) could hint\nat an archaeological record of decent size. Finally I would like to point out that the\ndating of the Khiamian material from this site is relatively early compared to the\nstandard time range proposed for the Levantine sites. Again an interesting detail that\ncould be further explored.\nWe are pleased the reviewer is convinced by the age and characterisation of the\noccupation associated with the rock art. The radiocarbon date from ARN3 Trench 2 falls\nright within the Khiamian tradition, while the OSL date from Trench 1 and the OSL date\nfrom Jebel Misma 8 overlap in range with it. Other finds from these sites point to a\nsubsequent PPNB occupation. We think there is strong reason to think these were the\ngroups who made the rock art since we have recovered an engraving stone in a dated\noccupation layer and there are no other candidate early occupations at these sites.\nWe agree with the reviewer that these sites are worthy of further exploration, but our\nfindings need to be published before we can seek further funding.\nReviewer #2 (Remarks to the Author):\nIn this article, the collaborating authors draw upon multiple strands of archaeological\nand paleoecological evidence to reconstruct a late Pleistocene-Early Holocene\nenvironment and populate it with fauna and human groups. For the latter, the\narchaeological evidence offers chronological and some cultural details such as technical\naffinities with northern traditions and long-distance exchanges of exotic materials.\nMobility of these human groups is implicit, by virtue of the seasonal availability of local\nresources and potentially by depictions of seasonal characteristics of fauna. A major\nfocus of this paper is the local rock art, studied in three newly reported locations and\nlinked to well-reported rock art studies across a broader region of northern Arabia.\nWhile rock art is rich in imagery and clues to the symbolism and communications of its\ncreators, it is rarely possible to date it or to link rock art unequivocally to other details of\nthe archaeological record. The significance of this paper lies in the assertion that the\nearliest phase of this reported rock art can be securely assigned to the Late Pleistocene-\nEarly Holocene transition and that the reported artifacts show an expansion of people\ninto formerly hyper-arid zones after the Pleistocene LGM abandonment. This argument\nsupposes that rock art of Phase 1 serves as a marker of human activity earlier than\npreviously documented Late Pleistocene-Early Holocene Arabia.\nwhich this reviewer is best qualified to assess. (Paleoecological details of sediment\ncharacteristics and dating methods underpinning the regional environmental\nreconstructions, including paleolacs, are not my forte). One strand is the age of the rock\nart and its indirect dating through purported association with artifacts. The second\nstrand is the absence of evidence for Late Pleistocene and Epipaleolithic occupation and\nuse of local resources to purport a re-population/expansion, driven by exogenous\nclimatic factors) into a region previously lacking human occupation. This second strand is\nthe major justification for publication in Nature Communications, even as the evidence\nand topic of rock art is intrinsically interesting, if localized. Similar and intrinsically\nlocalized evidence can be of the highest scientific interest, as studies of 40,000-year-old\ncave paintings in Southwest Sulawesi have demonstrated.\nWe thank the reviewer for their succinct summary of our paper and for highlighting the\nimportance and intrinsic interest of rock art research. We would like to clarify that the\nabsence of occupation is documented between the LGM and ~14ka; possible evidence\nof Epipalaeolithic occupation dating to 13.4 ka was documented at Sahout (Guagnin et\nal., 2023). We have added a sentence and two references in the first paragraph of the\ndiscussion to clarify the timing and nature of this gap in occupation.\nTo examine these arguments, therefore, some close consideration of the linkages and\nchronologies of rock art and excavations is warranted. While the evidence is well\npresented, very well illustrated, clearly organized, and amply supplemented with\nextensive online supplemental materials, there remain some ambiguities. It is fortuitous\nto find sediments sealing or obscuring rock art as was the case at site ARN3 T1. This is\nthe only fully reliable stratigraphic dating (indirect) for rock art.\nThe engraving stone must have been used to engrave one of the two camels above, as\nthere is no earlier (or later) rock art within a distance of 200 m from this site. Based on\nthe associated OSL date we assign these camels to the PPN (phase 3 and 4) of the rock\nart.\nA critical item therefore is the white camel (phase 1) on the panel ARN 3 with its legs\ncovered in sediment. The authors assign this to the Pre-Pottery Neolithic (layer 5 in ARN\nT1). With a rockfall (layer 4) overlying layer 5, the camel engraving (and all phase 1 rock\nart classed as contemporaneous with it by the authors) could be later than layer 5,\nengraved independently and sealed at a later date by rockfall. While the evidence is\nstrongly suggestive of a PPNA (not Natufian) association with layer 5 and therefore of\nthe rock art “engraving” of a camel, questions remain. The tool argued to be used for\nengraving is also described as a “pecking stone” (Supplement 3.3 p. 16-170, and this\npecking motion is also described in Supplement 3.4 p. 42 (Figure 37 on p. 44). I would\nlike to see clarification of\nA) The reasons for dating to Natufian (a few notched flakes and mortars) instead of\nPPNA (later, consistent with and unremarkable for other finds in Arabia, e.g.,\nJebel Oraf). Note another “pecking” tool recovered on the surface at ARN30 (rock\n7\nart production method not specified in Supplementary Table 1). Radiocarbon\ndates are consistent with PPNA, not Natufian—unless one reads the most ancient\nextent of the radiocarbon determination rather than its median.\nThis is a mis-understanding, we are claiming that the main occupation at Jebel\nArnaan (and the earlier phase of camel engraving) was PPNA not Natufian. We have\nreworded to clarify. We state that occasional typologically Natufian artefacts were\nrecovered, but we do not use these artefacts to date the rock art to the Natufian.\nThere is earlier rock art than the camels featuring human figures that could relate to\nthe Natufian, but this is not associated with datable archaeological contexts and\ntherefore not the subject of this paper. We have removed three of the mentions of\nthe Natufian from the paper to make it clearer that we think that large camel\ntradition belongs to the PPN.\nB) The difference between engraving and pecking and the reasoning for a pecking\ntool to be an engraving instrument. This is critical for the association of the tool\nin ARN3 T1 and the camel engraving above it. I suggest more text on how the\nrock art was produced (pecking, engraving, other?) and explanation whether\nproduction criteria was included in the analysis of phases/chronology—or do\ndifferent production techniques cross-cut the chronological assignments of\nphases? I also suggest (in light of the access challenges) that authors address\nwhether one or many people were needed and consider the person hours of\nlabor involved. These considerations may lead to further insights on group size,\nfrequency of passage, and community dynamics.\nThe engraving process can consist of 1 or 2 steps. First lines are pecked. This method\nis used in all known panels. Some images are “scraped” in a second step, which turns\nthe rougher pecked lines into smooth grooves. We have found both types of tools,\nbut the one described from the excavations in ARN3 T1 is a pecking rather than a\n“grooving” tool.\nWe have clarified this throughout the manuscript:\n We have included a description of engraving process in the “Archaeological\nexcavation” section: “Analysis of the engraved lines shows that all images\nwere pecked using a pecking tool. In some engravings, pecked lines were\nsmoothed in a second step, using a smoothing tool (Error! Reference\nsource not found. inset).”\n We have included an inset in the new Figure 4 that shows a close-up of\nthe pecked/engraved lines on ARN3.\n We have included a sentence in the “Artefact assemblage” section that\nexplains the tool was used to peck rather than smooth lines.\n We have changed the wording in the caption of Figure 6 to “pecking tool”\nto clarify this distinction.\nengraving these lines, but this would require a dedicated experimental study which is\nbeyond the scope of this paper.\nC) The reason the camel engraving cannot be later than layer 5, that is, PPNA\noccupants at layer 5. As I read their evidence, it is plausible that there is a\nabandonment layer, then layer 4, which covers the camel engraving of rock art\nphase 1). It is possible that the camel engraving postdates layer 5 (by an\nunspecified period of time) and pre-dates layer 4 collapse (documented by\nauthors in section Figure ). It would seem that a post PPNA composition of phase\n1 would be very much consistent with evidence elsewhere of PPNB cultural\ninfluences among populations in the north Arabian humid period.\nIf we assume that the camel engraving post-dates layer 5, then we have a pecking\nstone that shows signs of having been used to engrave sandstone, but no engraving\nto go with it. There are no earlier engravings below the two camels. We therefore\nassume that one of the camels above was produced with this tool.\nOur observations also show that engravings are normally placed higher up and not\ndirectly above the ground presumably to make pecking easier and protect the\nengravers’ hands. The ground surface would have been close to the camel’s feet\nduring the deposition of layer 4, making engraving difficult. While there does\nappear to have been PPNB occupation at Jebel Arnaan, the main occupation layers\nin both trenches date to the PPNA. We assume rock art phase 3 begins in the PPNA,\nbut large animal representations appear to have been produced over an extremely\nlong period and well into the PPNB.\nNote that if the evidence is stronger (as I read it to be) for PPNA not Natufian incursions\ninto the arid zone, the chronological assertions are less remarkable than the authors\nindicate, or they could be re-stated for local versus peninsular significance. (See Crassard\net al. 2013, cf., Hilbert et al. 2014 both cited by authors). Even so, the analysis classifying\ndifferent episodes of rock art based on stylistic grounds and overlap/superposition of\nimages is new and potentially foundational in the region.\nThe reviewer is correct, our present paper has stronger evidence for PPNA incursions.\nWe took the evidence for possible Natufian incursions from previous research at SAU, where\nwe have an even earlier radiocarbon age. We have re-worded this in the conclusion and\nalso referenced where the information comes from. We have reduced the claims for a\nNatufian presence although some of the artefacts (the Helwan bladelet and the opposed\nnotch blades) and some of the dates do still suggest this. We have clarified our\nargument that the life-sized naturalistic camel engraving tradition belongs to the PPN,\nnot the Natufian.\nThe second strand is the absence of evidence for Late Pleistocene and Epipaleolithic\noccupation (at this locale) and use of local resources to purport a re-population/expansion,\ndriven by exogenous climatic factors. The authors need to broaden the significance of this\npaper beyond the repopulation of this specific locale in the Arabian Peninsula. This might\nbe done by referencing other and adjacent geographies: the greening of the Sahara or the\nLGM refugium in the Arabian/Persian Gulf theory come to mind.\nEpipalaeolithic which was found during a fieldwork: a Middle Palaeolithic Levallois core.\nWe have added a reference to the site of Al Marrat 3, the youngest Middle Palaeolithic\nsite in northern Arabia, with no known intervening occupations between this and the\nsites documented in our project anywhere in northern Arabia.\nA few minor points:\nCaption in Figure 1 (main text) documents 131 rock art images, versus (in text) account\nof 176 images (line 150).\nText and caption both list 130 life-sized images (the text additionally lists “2 camel\nfootprints, 15 smaller 153 scale naturalistic depictions of camels, 19 human figures, 4\nhuman faces or masks, and 6 154 unidentified, partial engravings”. We have now\nincluded these in the caption.\nLine 234—dating the engraving of the camel by the height of its legs. Even if the\nauthors’ reasoning is sound (? See above), this line is confusing and needs to be clearer\nfor first reading.\nWe have changed the wording in this sentence to “the fact that the legs of the engraved\ncamels were covered with sand”.\nLine 297 and ff. lithics—Supplement p. 36 & Fig 20—that there is a transition in materials\nbetween PPNA and PPNB layers is interesting and deserves greater comment. A gap in\ntime? Different populations? Different economic pathways for the circulation of goods?\nWe agree with the reviewer that this is an interesting aspect of the archaeology worthy\nof greater comment, but it is beyond the scope of this paper. A follow-up paper in\npreparation focusses more on the lithics, including the silcrete source at Sahout and\ngeochemical provenancing of the obsidian. In this next paper we describe the mobility\nimplications of the differences in material between the PPNA and PPNB and we discuss\nthe issue of whether there is chronological hiatus using new dating evidence from\nSahout.\nLine 379 argues that engravings reflect a rainy season. I tend more to agree with the\nmultiple and sometime symbolic/ideological and/or social communications the authors\nexplore in discussion. It is altogether too easy to “read” as economic and functional-\nhistorical images one doesn’t access through cultural practice and initiation. I’d prefer to\nkeep the interpretation open and refrain from linking specifically to moisture/rainy\nseason.\nSupplementary Figure 10 has a dark shadow that obscures critical section information.\nThe authors would be forgiven for photoshop manipulation of this figure to illuminate\nany section details that can be discerned.\nWe have removed the shadow as much as possible (using Adobe lightroom).\nLikewise it is odd that the authors elected not to excavate fully adjacent/perpendicular to\nthe limestone face bearing the rock art (as they did in ARN3 T2). If this was done\nsubsequent to the image, a description of the lowest extent of phase 1 camel engraving\n(outlined in black) would be warranted.\nWe initially left a baulk between the trench and the engraving to protect the engraving\nduring excavation and to get a better view of the stratigraphy. This was later removed\n(see Supplementary Figure 11). The lowest extent of the camels (which are phase 3) is\nshown in the tracing provided in Figure 3, although the legs and feet of the earlier camel\nare partially eroded and no longer visible.\nWe have clarified with a note on the erosion of camel legs in the caption of Figure 4;\ninformation on the bulk and its removal in the caption of Supplementary Figure 10; and\nwe point out the removed baulk in the caption of Supplementary Figure 11.\nMissing references include other efforts at dating rock art in Arabia, either through\nindirect association with sediments (Rachad and Inizan’s work at Sa’ada, Yemen) or\nthrough stylistic classifications and their superposition in different panels (also used in\nthis manuscript) (e.g., Philby-Ryckmans’ expedition publications). Direct dating has\nrecently been possible with (organic) painting (Rowe et al. The Holocene 2022).\nWe have deliberately not referenced the superpositions described by the Philby-\nRyckmans’ expedition (photos of which were analysed by Anati), as these descriptions\nare now considered controversial by some researchers (Bednarik and Khan have written\nseveral critiques).\nWe have included a short section on rock art dating based on varnish analysis and\nreference work by (Andreae et al., 2020; Macholdt et al., 2018) that is specific to\npetroglyphs in Saudi Arabia in the “Monumental Rock Art” section. We have referenced\nfigures in the manuscript and SI that show rock varnish in our dataset, and we have\nincluded a close-up of pecked lines with patches of desert varnish in the new Figure 4.\nWe have also included a section explaining the context of rock varnish analyses in the\nDiscussion.\nReviewer #3 (Remarks to the Author):\nA very interesting piece of work. It is good to see the archaeology tied to the rock art,\ntogether with the various dating methods. A few remarks:\noutset)\nWe have changed the wording to “sandstone outcrops”.\nLine 160 (Fig. 1) A: Map could be larger and B possibly two gazelle and one goat\nA: We have increased the size of the map in a new standalone map Figure 1.\nB: Comparison with other panels that also show the bodies of gazelles suggests all three\nengravings also represent gazelles. Goats are now known in the rock art until the\nNeolithic, where they are generally shown with horns that curve upward in parallel and\nthen outward at the top, as well as with much more heavily set bodies (Stewart et al.,\n2024: Fig 6).\nLine 205 Freshly engraved INSERT COMMA the images…\nComma inserted.\nLine 366 omit comma\nComma deleted.\nLine 374 could the aurochs not be a record of what has been seen elsewhere?\nThat is exactly what we meant when we said “…or that during dry seasons human\npopulations retreated to wetter areas where aurochs were present”. For clarity, we have\nchanged the sentence to “…or that aurochs were seen elsewhere, perhaps when human\npopulations retreated to wetter areas where aurochs were present”.\nIn the paragraph starting on l. 431 maybe add something about representation of the\nanimals also being a record of the environment, potentially sympathetic magic, territorial\nmarkers, indications of herd movements (an extension of the statement about routes l.\n437),\nWe have re-worded the paragraph to include territorial markers. We would prefer not to\nspeculate on magic, as this draws parallels to much more recent customs in South\nAfrican rock art and we have no evidence for this interpretation.\nLine 489 the monumental rock art in Arabia sets them apart from the Levantines—maybe\na phrase to explain what sort of rock art was found in most of the Levant… Also, maybe\nworth noting that such monumental rock art is found in North Africa, though not in\nEgypt. And, it might be worthwhile speculating (if possible) why monumental images\nwere so common here.\nWe would like to avoid comparisons with the Levant and the Sahara at this point. Such a\ncomparison warrants a much more detailed article. Part of the problem is also that to\ndate only very little rock art that pre-dates the Iron Age is known from the Levant.\nbeen discovered in Jordan but has not yet been published. At present this prevents any\nmeaningful comparison between both regions.\nWhat animal bones were recovered from the area? Can these be linked to the rock art?\nWe provide a report on the faunal remains in Supplementary Note 4. Sadly, the material\nwas so badly preserved that no species identifications were possible, with exception of a\npiece of ostrich eggshell.\nReviewer #4 (Remarks to the Author):\nThe manuscript entitled: “Monumental rock art illustrates that humans thrived in the\nArabian Desert during the Pleistocene-Holocene transition” presents highly original data\nfrom a key archaeological site in Northern Arabia. With regard to the interdisciplinary\nscope and the relevance of the topic presented in the Ms I have no doubt that this\nmanuscript is a potential very good fit for Nature Communications as it is relevant for\nthe broader scientific community. Also, with regard to the highly original multi-method\ndataset this Ms deserves publication in a high-ranking outlet. However, I was a bit less\nimpressed with the structure and conciseness of the main manuscript. The manuscripts is\noccasionally redundant and the argumentation is – at least party – not convincingly\nstructured. Even more importantly it is oftentimes difficult to trace back the scientific\nevidence that should support the argument/interpretation. Also, some of the figures\nneed to be improved especially with regard to their self-explanatory power. From my\nperspective it is crucially important that the actual scientific evidence is directly\nassociable with the corresponding figure (especially Fig. 6) or interpretation. In summary,\nI see the high potential of the paper and I am convinced that it can have a significant\nscientific impact, however, a major revision is required to make it fit for publication.\nBelow I provide some feedback that will hopefully help to make the Ms more concise.\nWith regard to the supplement, I focused on the geomorphological (note 5) and the\nluminescence data (note 6) and provide some additional feedback especially with regard\nto documentation and interpretation.\nWe thank the reviewer for highlighting the relevance and importance of our manuscript.\nWe have improved the structure of the manuscript to make our argument more concise:\n We have re-written the paragraph introducing our research.\n We clarify how rock varnish indicates the age of engravings and referenced\nrecent research.\n We have linked figures better with evidence from scientific dating and now\ninclude dating information in figures 3, 4 and 7.\n In the discussion we have made our statement on potential aurochs movements\nmore concise, and we have clarified the link between the excavated pecking tool\nand engraved rock art.\n We have shortened the conclusion to provide better focus on our results, while\nproviding additional references for comparative information.\nsee responses to comments below):\n We now provide a stand-alone map in figure 1 that gives a better overview of the\nsites and landscape.\n We provide an extended selection of engravings in the new figure 2.\n We provide additional information on sediments and engraving in the section\ndrawing in figure 4.\n We have provided more extensive information in the caption of figure 7 (formerly\nfigure 6).\n We have provided clearer maps in figure 8.\nMajor comments:\n1) Introduction line 74ff: I do not find it helpful that the authors provide a summary\nalready in the introduction, which will ultimately cause redundance. Maybe it’s\na matter of personal taste but to me this para reads a bit like a cheap sales-\npitch. I‘d recommend to use this space to more convincingly carve out the goal\nsetting of the paper and maybe establish some main hypothesis here.\nWe have re-written this paragraph to state our initial hypotheses rather than pre-empt\nresults.\n2) Figure 1, line 159f: also, I’d recommend to redo this figure, especially sub-\nfigure A. The informative value of the maps shown in supplementary figure 40\nis much higher and they also meet scientific standards with regard to north\narrow and a prober scale. Throughout the main manuscript I found it difficult to\nlink the archaeological as well as sedimentological findings to the\ngeographical/geomorphological context. A better map shown here could be of\ntremendous help in that regard. Regarding sub-figure B to D I think a readable\nscale is missing. I know there is one in the photo, however, it is almost\nimpossible to read and to use as a prober scale.\nWe have increased the size of the map and turned it into a standalone figure (new\nFigure 1). We have also included a north arrow.\nWe have made a new Figure 2 with the rock art images. We now clearly indicate the\nsize of the scale in the caption.\n3) Sampling context (e.g. Fig. 2 but also more general): It is difficult for readers\nwho have not been part of the excavations to link the archaeological\nexcavations to the sampling context for sedimentological and geochronological\nanalyses. For example, in Fig. 2 it would be nice to get a direct impression\nwhere the sampling site for OSL and radiocarbon dating is located and what the\nconnection between the engravings and the geological record is. This link\nneeds to be easily traceable in the main manuscript as it provides a main line\nof evidence for the later interpretation e.g. presented in Fig. 6 and the\ndiscussion section.\nincluded a description of the playa sampling location and a reference to Figure 8 which\nshows them on a satellite image. The new Figure 1 with the larger map should also\nmake these correlations clearer.\n4) Interpretation of playa sedimentation (e.g. line 360, or supplement 5 section\n5.3.): the authors use playa sedimentation as a local paleoenvironmental\nrecords especially with regard to water availability, which generally is a good\nidea. However, the authors ignore in their analyses and interpretation of the\nrecord that wind erosion could have played a significant role in forming this\nplaya sediment successions, which would imply that the claim of the first humid\nphase since the LGM is a bit on shaky ground. Alternatively, one could interpret\nthat a previous humid phase is missing in the record either because there was\nnot enough water available in the catchment to form playa sediments prior to\nthis phase or the corresponding playa sediments had been subsequently\neroded by wind erosion during a dryer phase. From my perspective are both\nscenarios possible with an almost equal probability.\nThe reviewer has raised a good point here that we did not articulate in the paper. We\nhave now added three sentences that address this issue by discussing how the\nbalance between aeolian erosion changed from the LGM to the Holocene:\n“We interpret the onset of playa sediment accretion as representing the change in the\nbalance between aeolian erosion and fluvial sedimentation. During the LGM the hyper\narid environment meant that any fine-grained sediments deposited in ephemeral\nfloods were subsequently eroded by the wind. As the climate became less arid, fluvial\nsedimentation increased, becoming greater than the aeolian erosion rate and\nsediments started to accumulate.”\n5) Interpretation of the results (e.g. Fig. 6): as addressed already in my major\ncomment#3 it is very difficult trace back the actual evidence that form the basis\nfor the interpretations presented in this section and figure 6. As this is a scientific\npaper and journal, I think that the connection between the argument and the\nunderlying scientific evidence should be as strong as possible. That said, I\nrecommend to majorly revise Fig. 6 with the goal to make all links to the actual\nscientific evidence clearly visible. For example, the interpretation of the\nenvironmental context in the very right column, what is it actually based upon?\nThe evidence needs to be directly traceable. Same with the columns human\nactivity and rock art.\nAs stated in the caption, all information provided in black font reflects results and\ninterpretation provided in the text. We have added more detailed statements of what\nevidence each set of data is based on in the caption to provide more clarity. The key\npieces of human activity and rock art evidence are described on the figure itself. For\nthe environmental evidence in order to keep the figure easy to read it is best to provide\nthe basis for the interpretation in the caption rather than in the figure itself.\nsedimentology and chronology as discussed in the text.\n6) Supplement 5, Figure 42: the header “grainsize and texture” is a bit to vague.\nWhat statistical parameter did you use to describe the underlying distribution of\ngrainsizes? Is it D50 or something else?\nGrain size and sorting was observed visually and textually in the field and classified\naccording to standard the sedimentological classification. This information has now\nbeen added to Supplementary Note 5.\n7) Supplement 5, Figure 42 and page 56, section 5.3: why was the sandy gravel\nlayer only sampled for dating in JMI and not in ARN? With only one age on this\nunit the interpretation that it belongs to very late MIS5 (page 56, section 5.3 first\npara of this section) is shaky and I think this should be highlighted in the text.\nWe attempted to sample the gravel. However, it was very coarse and the OSL tube\nwould not penetrate. Furthermore, a block sample also failed as the sediments were\nnot cemented. The late MIS5 age is consistent with other evidence for humidity in\nnorthern Arabia during this period which we cite in supplementary references 37-40.\n8) Supplement 6: to show the general robustness of both the multiple-grain as well\nas the single-grain results the authors need to show dose recovery results,\nwhich is the standard performance test. Without dose recovery results the\nluminescence data is difficult to trust.\nDose recovery tests were performed on five of the eight samples presented in this\nstudy, with all five samples yielding acceptable (within 2σ of unity) ratios. This\ninformation has been added to Section 6.1.4 of the Supplementary Notes.\n9) Supplement 6, section 6.1.5: to be able to judge on the appropriateness of the\ninterpretation of the De distributions and the application of the different age\nmodels to obtain the burial dose I strongly recommend to provide De\ndistributions (preferably as radial plots but KDE plots would also work) in\nsupplement 6. Without De distribution is difficult to judge on the robustness of\nthe obtained Db and thus OSL ages.\nThese plots have been added as Supplementary Figure 45.\n10) Supplement 6, section 6.1.5: The use of the FMM for sample JMI8-T1-4 seems\nproblematic to me in this context.\na. To me the more appropriate age model for this sample would be the\nMAM especially when using the bootstrap version (Cunningham and\nWallinga 2012) where sigma_b can be assigned with an uncertainty (e.g.\n25 ± 5%).\nb. The FMM would only make sense if the sample is “contaminated” ´with\nyoung dose grains, something the authors recognize themselves\n(section 6.1.5, first para, last sentences), as the MAM would have\ndifficulties to handle these lowdose outliers/population. However, in the\nnext paragraph of section 6.1.5 you write that sample JMI8-T1-4 showed\n16\nhigh-dose grains presumably resulting from “contamination” from older\nand not younger grains. So, there is no added value in applying the FMM\nhere.\nc. The way sigma_b is determined by basically doing a sensitivity analysis\nusing the FMM is not stringent if you ask me. The sigma_b describes the\nunexplained scatter in the De distribution for a perfectly bleached and\nun-mixed sample. As you have samples that seem to behave this way, I\nstrongly recommend to apply single-grain measurements to one of your\nwell-behaving samples and use the obtained over-dispersion as input\nsigma_b for Db determination of sample JMI8-T1-4. If you apply the\nbootstrap MAM (and I think you should) you can assign an uncertainty\nto this sigma_b (e.g. 20 % relative uncertainty), which is more realistic\nthen using sigma_b without any uncertainty.\nIn relation to points a and b, the MAM is very susceptible to being biased towards\nindividual low values yielding inappropriately young ages (e.g. Rodnight et al., 2006 ).\nThe bootstrapped MAM is an attempt to circumvent this failing, but it requires an\nappropriate sigma b value (see above) and remains sensitive to anomalously young\ngrains within a small dataset. Owing to the very low yield of acceptable grains from\nJMI8-4, and the limited amount of material available from MIS-B-3, both datasets are\nsmall. Furthermore, JMI8-4 contains 1 anomalously young grain, meaning that\nReviewer 4’s point b does not apply (though they couldn’t have known that without the\ndose distribution diagrams for the single-grain datasets, which they correctly asked us\nto add to the paper).\nIn relation to point c, there are two main objections. Firstly, the sigma b determination\nprocedure used here is entirely standard and has been routinely used in the literature\nfor nearly two decades (e.g. Jacobs et al., 2008, Section 9.1); it essentially balances\nimprovement of the fit to the data (maximum log likelihood) with an assessment of the\nminimum number of components required to explain the data (Bayesian information\ncriterion). This could be characterised as a “sensitivity analysis”, but it is still a sensible\napproach to fitting the data. Secondly, the samples have a low intrinsic luminescence\nsensitivity and low a low equivalent dose, meaning that the yield of measurable grains\nis ~ 0.002%. Assuming that well-bleached samples from the study area are a good\nanalogue for JMI8-T1-4 (not necessarily a given), generation of a large enough dataset\nto precisely constrain sigma b would be prohibitively time-consuming. Given that a\nwidely used and well accepted approach to determining sigma b from the JMI8-T1-4\ndataset itself exists, we have preferred to use that method.\nSome additional minor comments:\n11) Line 196ff: Please rephrase these two sentences starting with “The engravers….”.\nThere are non-scientific and speculative.\nThese observations are based on experiments and on our experience in the field. We\nhave changed the wording and now start the sentence with: “The friable nature of the\nsubstrate and the slope of the narrow ledge suggest…”. We have rephrased to say\n17\nthey ‘likely risked their lives’ rather than they ‘must have’, but the risk is clear and\nalready stated in the previous sentence as to why these panels were recorded with a\ndrone.\n12) Line 204ff: also, here I recommend to tone down the overly sensational tone of this\nparagraph.\nWe have rewritten the first sentence of this paragraph and removed the speculation\nto ‘even millennia’.\n13) Figure 3: please provide the ages in the figure to make it easier to ling engravings to\nthe geochronological framework (also see my main comment#3). Also provide some\nmore details on the kind of sand (e.g. with regard to texture, bedding structures)\ndeposited here.\nWe have amended the figure to include the OSL ages and details on the sand directly\nin the section drawing.\n14) Line 400: “…pre-date the tradition of life-sized camel engravings…”  which is\nevidenced by?\nThey must be older because they were found underneath later camel engravings. We\nhave changed the wording to make this clearer: “…stylised human figures (rock art\nphase 2, Error! Reference source not found.D) were repeatedly found below\nengravings of life-sized camels (phase 3). These human figures consequently pre-\ndate engravings such as those at ARN3, and are thus likely older than 12 ka (Error!\nReference source not found.).”\n15) Figure 7: where is North?\nWe follow the convention of having north at the top of all maps. We have now included\nnorth arrows to avoid any confusion.\n16) Supplement 6, page 59, section 6.1.4: please state size of the multiple-grain\naliquots\nThis information has been added to the first line of section 6.1.4.\n17) Supplement 6, page 59, section 6.1.4: indicate in table 8 which ages are based on\nmultiplegrain and which ages are based on single-grain measurements to make it\neasier to follow. That said, I‘d also add the information on the age model applied to the\ntable.\nThis information has been added to the caption of Supplementary Table 8.\n18) Supplement 6, page 59, section 6.1.4: why was an exponential plus linear fit of the\ndose response curve was used? There is no reason based on physics to use this.\nTrue, but there is a practical reason, which is that the exponential plus linear fit is often\nthe best fit to the measured data. In principle, dose response curves should be best\ndescribed by a single saturating exponential (the single-trap model) or by the sum of\ntwo or more saturating exponentials (two or more traps). In practice, the single\nexponential fit does not always adequately describe measured dose response curves,\nand curve fitting software does not invariably produce convincing fits using two or more\nsaturating exponentials, so the saturating exponential plus linear fit is a pragmatic (and\n18\nwidely adopted) solution. At large equivalent doses (>~100 Gy), use of different fits\ncan have a statistically significant effect on the calculated equivalent dose, and careful\njustification of the model used is necessary. Conversely, in the present study, all of the\nages supporting the archaeological argument are derived from samples with\nequivalent doses <40 Gy, in which case most of the dose response curve shape is\nderived from the saturating exponential component of the fit i.e. the difference between\na saturating exponential fit with or without a linear component is negligible.\nConsequently, we have retained the exponential plus linear fitting used in the previous\niteration of the manuscript.\nReferences cited in the response\nAndreae, M. O., Al-Amri, A. M., Andreae, C. M., Guagnin, M., Haug, G., Jochum, K.\nP., Stoll, B. & Weis, U. 2020. Archaeometric studies on pretroglyphs and rock\nvarnish at Kilwa and Sakaka, northern Saudi Arabia. Arabian archaeology and\nepigraphy, 31, 219-244. http://dx.doi.org/10.1111/aae.12167\nCharloux, G., Guagnin, M., Alsharekh, A. & Petraglia, M. D. 2022. A Rock Art\nTradition of Life-sized Naturalistic Engravings of Camels in Northern Arabia:\nNew Insights on the Mobility of Neolithic populations in the Nafud Desert.\nAntiquity Project Gallery, 96, 1301-1309. https://doi.org/10.15184/aqy.2022.95\nGuagnin, M., Charloux, G., Alsharekh, A. M., Crassard, R., Hilbert, Y. H., Andreae,\nM. O., Preusser, F., Dubois, F., Burgos, F., Flohr, P., Stewart, M., Mora, P.,\nAlqaeed, A. & Alali, Y. 2021. Life-sized Neolithic camel sculptures in Arabia: A\nscientific assessment of the craftsmanship and age of the Camel Site reliefs.\nJournal of Archaeological Science: Reports, 103165.\nhttps://doi.org/10.1016/j.jasrep.2021.103165\nGuagnin, M., Shipton, C., Stileman, F., Jibreen, F., Alsulaimi, M., Breeze, P. S.,\nStewart, M., Hatton, A., Drake, N. A., Jha, D. K., Al-Tamimi, F., Al-Shamry, M.,\nAl-Shammari, M., Kay, A., Groucutt, H. S., Alsharekh, A. M. & Petraglia, M. D.\n2023. Before the Holocene humid period: Life-sized camel engravings and\nearly occupations on the southern edge of the Nefud Desert. Archaeological\nResearch in Asia, 36, 100483. https://doi.org/10.1016/j.ara.2023.100483\nHilbert, Y. H., Clemente-Conte, I., Crassard, R., Charloux, G., Guagnin, M. &\nAlsharekh, A. M. 2022. Traceological analysis of lithics from the Camel Site,\nal-Jawf, Saudi Arabia: an experimental approach to identifying mineral\nprocessing activities using silcrete tools. Archaeological and Anthropological\nSciences, 14, 93. 10.1007/s12520-022-01559-6\nJacobs, Z., Wintle, A. G., Duller, G. a. T., Roberts, R. G. & Wadley, L. 2008. New\nages for the post-Howiesons Poort, late and final Middle Stone Age at Sibudu,\nSouth Africa. Journal of Archaeological Science, 35, 1790-1807.\nhttps://doi.org/10.1016/j.jas.2007.11.028\nMacholdt, D. S., Al-Amri, A. M., Tuffaha, H. T., Jochum, K. P. & Andreae, M. O. 2018.\nGrowth of desert varnish on petroglyphs from Jubbah and Shuwaymis, Ha’il\nregion, Saudi Arabia. The Holocene.\nhttps://doi.org/10.1177/0959683618777075\nRose, J. I. 2022. Seeking Solace (50–12 Ka). In: Rose, J. I. (ed.) An Introduction to\nHuman Prehistory in Arabia: The Lost World of the Southern Crescent. Cham:\nSpringer International Publishing, 231-255. 10.1007/978-3-030-95667-7_10\nHatton, A., Alqahtani, M., Zalmout, I., Clark-Wilson, R., Al-Mufarreh, Y. S. A.,\nAl-Shanti, M., Zahrani, B., Al Omari, A., Al-Jibreen, F., Alsharekh, A. M., Scerri,\nE. M. L., Boivin, N., Petraglia, M. D. & Groucutt, H. S. 2024. First evidence for\nhuman occupation of a lava tube in Arabia: The archaeology of Umm Jirsan\nCave and its surroundings, northern Saudi Arabia. PLOS ONE, 19, e0299292.\n10.1371/journal.pone.0299292\nWe thank the reviewers for the time they have taken to review our manuscript a\nsecond time. We are pleased all issues are now resolved. The reviewers’ comments\nhave improved the quality and readability of our manuscript.\nReviewer #1 (Remarks to the Author):\nI thank the authors for considering all my suggestions. The paper is now in a state where I\ncan recommend publishing it.\nWe are glad all issues are resolved.\nReviewer #2 (Remarks to the Author):\nThis is my second review, and I am grateful for an opportunity to see the changes made to\nthe manuscript as well as the issues raised and responses to other reviewers. I consider this\nprocess akin to joining a review panel or scholarly jury after consideration and review of the\nwork by myself. This comment is therefore influenced by my readings of other reviewer-\npeers and of course by my own re-consideration of manuscript and revisions. I caution that I\nhave provided a more cursory reading than on first review. It is interesting to see that\nreviewers have raised some of the same concerns and points while bringing different\nexpertises to this review.\nI find that the authors have made substantive, highly informed and generally persuasive\nresponses to the many detailed comments we reviewers have raised. There is no doubt that\nthis work is of highest quality, that the methods and analyses are sound, cautious, and\naddress significant questions. Notably, the repopulation and adaptations of human groups\nto arid environments has significance beyond the data set represented by this small cluster\nof sites in Northern Arabia.\nWe thank the reviewer for their positive assessment of our revised manuscript.\nMy lingering concern is the regrettable paucity of evidence that links the first phase (camel\nimages) of petroglyphs to PPNA (the authors have corrected prior text that led me to\nsuppose they argued a Natufian date). The interpretation still hangs on one\npecking/engraving stone found 72 cm away near the top of a layer dated by OSL and by a\nhearth (14C) in a different trench. The excavation is small; as much as I sympathize with the\nauthors' urgency to publish before seeking additional funding to expand the data set (their\nletter of reply), I worry that their interpretation still has privileges to an earlier date over\npotential explanation for a later one. 200 m is not so very far to transport a pecking tool\n(from a later engraving phase), possibly with the intent to use it, but instead it was lost or\nabandoned. It is my experience that sedimentation in the desert is neither continuous nor\nsolely depositional. Where material accumulates (layer 5), it can also blow away, leaving\nheavier stone on the surface (desert reg). This can happen multiple times; thus what\nappears to be the upper part of layer 5 can reflect an accumulation of artifacts of different\nages and sources. Again, the evidence would be more compelling if the hearth was nearer\nthe camel, if the camel legs were clearly complete, if there were more pecking stones or it\nsat in a dated hearth, or if the trench were extended to join the trench where the dated\nhearth occurs.\nThe reviewer is correct that sediment in the desert often blows away. However, in the\ncase of the ARN T2 excavations refits from layers 8 and 9 attest to the high integrity\nof the archaeological context.\nWe have included a caveat in our discussion: “Nevertheless, the possibility that the\nengraving tool was transported from a different panel at Jebel Arnaan, cannot be\nexcluded entirely.”\nArchaeologists cannot always obtain the richness of data they would prefer—discovery\nrelies on chance and expertise. My point is not to discredit the excellent work the authors\nhave done, and their high expertise is evident.\nWe thank the reviewer for their positive assessment of our work. We agree that it is not\nalways possible to obtain the richness of data we would all prefer.\nReviewer #3 (Remarks to the Author):\nThe revised work reads much better and address all the reviewers' concerns.\nI agree with the authors that the artefacts for creating the images would be beneath (maybe\nwell beneath) the images, though it is always tricky with rock art to always link archaeology\nto particular works.\nIt is hoped that more funding is forthcoming so that the authors can return to the site and\nextend the area of excavation.\nWe thank the reviewer for their assessment and are pleased all concerns are resolved. We\nagree that more funding and further excavations would help our understanding of these\nearly sites.\nReviewer #4 (Remarks to the Author):\nI would like to thank the authors for their detailed rebuttal. As a result of I think that the\nrevised manuscript is much improved and that my main concerns are sufficiently addressed.\nI am happy to recommend the Ms for publication in Nat.Comm.\nWe thank the reviewer for their positive feedback. We are happy all concerns are now\naddressed."}]

Decision letter