Progress in Land Transportation System as a Factorof the State Formation in JapanTANAKA Yutaka1(translated by SASAKI Ken’ichi2)
ABSTRACTThis paper is an approach to the state formation in Japan from the standpoint of transportation.
Until the fourth century A.D. Japan lacked wheel transport. People had to depend on watertransportation. Although standardized keyhole-shaped mounded tombs appeared in the middle
third century, a network symbolized by sharing the keyhole-shape for elite burial was still weak.
In the ﬁfth century, horses were introduced to Japan, which made land transportation easy. The
impact of the introduction was considerable in mountainous regions in eastern Japan. This also
affected the selection of a site for building a giant elite mounded tomb. Furthermore, regional
differences in pottery styles disappeared in the ﬁfth century. This progress in the ﬁfth century
contributed to the social evolution at that time greatly.
KEYWORDS: State formation, Japan, Kofun Period, transportation system

1.

Introduction

Late prehistoric and protohistoric Japan presents a very interesting case of a change intransportation system as a factor of early state formation. This must be understood in thecontext of interactions between human activities and environment. In the third century
A.D. or a transitional phase from the Yayoi) to Kofun Periods,1) local communities cameto be tied into a single network, encompassing 1000 kilometers from west to east. This
happened within a century or maybe within ﬁfty years. Such a tie that formed in a shorttime period is considered weak, but in Japan this tie has never collapsed since the third
century.

2. Premise
The Japanese islands in the third century were characterized by a very neat balance
between environmental conditions and cultural conditions. The environmental conditions
1 Facultyof Humanities and Social Sciences, Ibaraki University, Mito, Ibaraki 310–8512, Japan(yutaka.tanaka.archaeo@vc.ibaraki.ac.jp)
2 Faculty of Arts and Letters, Meiji University, Chiyoda-ku, Tokyo 101–8301 (ksasaki@meiji.ac.jp)
Category: Original Article Received: 23 June 2017; Accepted: 12 September 2017
JAPANESE JOURNAL OF ARCHAEOLOGY 5 (2017): 26–43

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included a geographical position of the Japanese islands within East Asia, oceanic tides,
arrangement of the Japanese islands, minor topography, ﬂora and fauna. The cultural
conditions included technology, tools, architectural structures, populations, knowledge,
personal ties, and organization. These natural and cultural conditions interplayed with
one another, and this interplay inﬂuenced human activities, and the human activities also
inﬂuenced the interplay.
My approach to history from the standpoint of interaction among human activities,
environmental conditions and cultural conditions is somewhat close to systems theory
and ecological approach to archaeology (e.g. Flannery 1968; Ford 1979). I believe thatanalyses of environmental differences and changes that may facilitate or trigger changes
social evolution will lead us to dynamic understanding of human history.
It is taken for granted that a street, bridge, and port are consequences of humanactions that modiﬁed or changed the natural and environmental conditions. The newenvironment as a result of human activities also inﬂuences human activities. An aspectthat I pay particular attention to is that, although a change in the natural environment
is not obvious, the change in the natural environment by human activities considerably
inﬂuences human activities. It is important to note that minute modiﬁcation in thecultural and natural conditions may result in drastic change.
A good example is the invention of a boat. Prior to the invention, people had to swim
to cross water. At that time, a river, swamp, lake and ocean were a natural condition
that acted as a barrier against transportation of goods. Once the invention occurred,a gentle stream and still swamp and lake were transformed into an effective mean oftransportation. When a dug-out canoe was only available, a major river with rapid
current and ocean with strong tide still remained as a barrier against transportation.2)
These examples vividly illustrate that, while the natural environment remains unchanged,a change in cultural conditions can considerably transform what the natural environment
means to people.
When we look into the detail of this interplay between a boat and water, numerous
factors must be taken into consideration. Cultural factors include people’s accumulated
knowledge about tide level, ocean current, topography and the locations of other groupsof people, as well as personal ties with other groups with which people exchangecommodities and means to check the activities of groups in competition. Natural factors
include the width, depth and the speed of current of a river, topography of coast lines,
ocean current, tide level, and climate. A complex interplay of these factors constitutes tothe water transportation system.
In consideration of the social evolution during the Kofun Period, additional culturaland natural factors should be considered. Such cultural factors are geographical positionsof communities in relation to iron sources in the Korean peninsula and transportation© Japanese Archaeological Association

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TANAKA Yutaka

Figure 1.

Japanese Islands

systems available at that time, and natural factors are a geographical position of theJapanese islands within East Asia, and arrangement of the Japanese islands (Figure 1).

3.

Water transportation network before the fourth century

The Kofun Period started in the middle third century, when the standardized keyholeshaped burial tombs appeared in numerous regions in western Japan. This was a marked
departure from the Yayoi Period when mortuary customs were regionally distinctive.
By “standardization of the mound form,” Kofun Period specialists in Japan mean thata ratios among the diameter and height of circular rear mound, width and height oftrapezoidal frontal mound, and width and height of the joint between the rear and frontal
mounds are shared by several keyhole-shaped mounded tombs built in different regions.
Japanese archaeologists assume that the highest- and higher- ranking chiefs in the central
polity distributed the construction-plan of a mound to local elites as a sign of alliance orfriendship (Wada 1981; Hōjō 1986). Within one hundred or maybe ﬁfty years, keyholeshaped mounded tombs were distributed all over the Japanese islands, except for the
Ryukyu Islands and Hokkaido, spatially extending more than 1000 km.
Despite this drastic change, the transportation system at the beginning of the Kofun© Japanese Archaeological Association

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PROGRESS IN LAND TRANSPORTATION SYSTEM AS A FACTOR OF THE STATE FORMATION IN JAPAN

Figure 2.

Cultural condition in 3rd century Japan

Period was very limited. Japan at that time lacked horses and cattle, as recorded in
the Wei-Zhi [the ofﬁcial history of Wei China]. Recent accumulation of archaeologicalevidence dated to the third and fourth century gives support for this description of
written source (Tamura 2005). Third century Japan also lacked wheel transportation andsailing ships. The oldest evidence for wheels in Japan was excavated beside the Kodachi
Mounded Tomb in Nara Prefecture. While the tomb is dated to the ﬁfth century, thewheel was discovered in a stratum dated to the seventh century when the Abe-Yamada
ancient highway running beside the tomb was in use.
Let me ﬁrst review the situation before the third century (Figure 2). In the ﬁrst century,
stone tools were replaced by iron. Since local production of iron started in Japan in thesixth century, iron ingots had to be imported from the Korean peninsula. This meansthat it was important for local communities to secure transportation routes in order toconstantly obtain iron transported for a long distance. It is easy to imagine that people inthe ﬁrst and second centuries or the Late Yayoi Period chose water transportation because
carrying or dragging iron ingots overland within Japan was far less efﬁcient. This choiceof water transportation greatly inﬂuenced the geographical locations of settlements.
In the Kanto plain in eastern Japan where the Tokyo Metropolitan Prefecture issituated in its southern one third, small tablelands of 20 to 50 meters in height and© Japanese Archaeological Association

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Figure 3.

Kanto plain

streams are located side by side (Figure 3). These streams are divided into the westerntributary system that ﬂows into the Tokyo Bay and the eastern tributary system thatﬂows into the Paciﬁc Ocean. These two tributary systems were separated by a divide orwatershed running north-south, but the divide is a height of only 20 meters in height.
In second century Japan, however, this watershed functioned as a cultural boundary.
Not only was this a boundary of regional characteristics of pottery use, but also thisboundary marked the eastern frontier of the typical Yayoi material culture that diffusedfrom the west, including moated burial precincts, moated settlements, and iron daggers(Figure 4). Although the watershed was a height of only 20 meters in height, it was
the major obstacle of transportation for people who had to acquire the daily necessities
from outside and to whom horses and cattle were not available. In other words, people
depended exclusively on water transportation, fully utilizing boats of various sizes. Landtransportation played the minimum role.
At that time, an ideal water transportation route that connected the coastal area of
the Tokyo Bay and the eastern Kanto plain, crossing the watershed, was a short-cut
route that connected the northern coastal area of the Tokyo Bay and the Imba swamp.
They could not yet sail around the Bōsō peninsula, which was a dangerous journey.
Settlements dated to the second to fourth centuries in this region are not situated in land
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Figure 4.

Cultural boundary in 2nd Century Kanto

suitable for wet rice cultivation but along the ideal water transportation route. Indeed,
coastal/riverine areas were not particularly good for rice cultivation. At a locality whereland transportation was unavoidable, a site of iron smith was located. These lines ofevidence clearly indicate that people depended on iron transported for a long distanceand were very conscientious about water transportation.
After the Kofun Period started in the middle third century, keyhole-shaped mounded
tombs were built at many different regions of Japan. These keyhole-shaped mounded
tombs were built according to ﬁxed standards, such as ratios between the length, width,and height, and were marked by clear differences in scales. This indicates that leaders of
local polities were incorporated into a network that also symbolized the different ranksof the local leaders in relations to one another within the network.
Keyhole-shaped mounded tombs in the late third and fourth centuries are located along
relatively narrow and easy rivers, especially conﬂuences or a point where a valley meetsa plain. These locations should be considered as a “point of change-over in transportationmeans.” Among these keyhole-shaped mounded tombs, those presumed to be the burialof the highest-ranking chief in a region tend to be located at upper but easy streams. For
example, giant keyhole-shaped mounded tombs of around 300 meters in length, presumed
to be the burials of the highest-ranking chiefs of the central polity, are located in thesoutheastern corner of the Nara basin, where the Yamato River ﬂowing out of a mountainreaches the basin. At the border of the Nara basin and Osaka plain where other streams
ﬂow into the Yamato River, smaller mounded tombs are distributed (Figures 5, 6).
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Figure 5.

Yamato river

Figure 6.

Giant burial mounds in 3rd–4th Century Nara Basin© Japanese Archaeological Association

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Figure 7.

Chikuma River and Sakura River

This is also the case in eastern Japan (Figure 7). Along the Chikuma River that ﬂows
through the Zenkōji basin in the northern Nagano Prefecture of the central highlands ofJapan, fourth century mounded tombs are located at the upstream and downstream ofthe basin as well as where the Sai River meets the Chikuma River. The largest keyholeshaped mounded tomb in the basin is located at the upstream on the Chikuma Riverin the basin (Figure 8). In Ibaraki Prefecture in northern Kanto, large keyhole-shaped
mounded tombs are located at the upstreams of middle-class rivers (Figure 9).
These examples suggest to me that elite mounded tombs were located at “points ofchange-over in transportation means,” and the location of the largest keyhole-shaped
mounded tomb in a region at the upper but easy stream symbolized the upper limit of the
maximum utilization of water transportation by river.
Yet, the situation in western Japan should be distinguished from eastern Japan forseveral reasons. First, western Japan was closer to the Korean peninsula. Second, theInland Sea functioned as the major transportation route of importing iron. Indeed, late
third century keyhole-shaped mounded tombs were located on the coastal regions of theInland Sea (Figure 10). This suggests to me that the early Yamato polity with the centerin Nara (Yamato) was a confederacy in nature of regional polities in the coastal regionsof the Inland Sea in order to secure and stabilize the Inland Sea transportation. This
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TANAKA Yutaka

Figure 8.

Burial mounds in 4th Century Middle Chikuma River

Figure 9.

Burial mounds in 4th Century Sakura River

linear network based on water transportation that tied regions somewhat distant from one
another resulted in a rather uneven spatial distribution of the late third century keyholeshaped mounded tombs in the Inland Sea regions. The eastern end of the Inland Sea is© Japanese Archaeological Association

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PROGRESS IN LAND TRANSPORTATION SYSTEM AS A FACTOR OF THE STATE FORMATION IN JAPAN

Figure 10.

Earliest type of Keyhole-shaped burial mounds (3rd Century)

Figure 11.

Nara Basin and the Watershed

the Osaka Bay, and the Nara basin is located behind the Osaka Bay.
As aforementioned, the burial of the highest-ranking chief of the central Yamato polity
was located in the southeastern corner of the Nara basin, at the foot of watershed that
separated spheres of transportation between western and eastern Japan (Figure 11). In© Japanese Archaeological Association

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other words, the burial of the highest-ranking chief was located at the eastern end ofwestern Japan advantageous in water transportation and at the entrance to eastern Japan
disadvantageous in water transportation. A factor that had put the central Yamato polity
in a more advantageous position than other polities was its geographical position under
the condition of heavy dependence on water transportation and with an expectation forcontrol over transportation in eastern Japan.3)

4. Land transportation as an epoch in the network system in theﬁfth century
From the end of the fourth century to middle ﬁfth century, horses were introduced toJapan from the Korean peninsula, probably for military purpose. Once horses wereintroduced in the ﬁfth century, horses were quickly adopted in Kyushu closest to the
Korean peninsula and the Osaka-Nara region where the central polity existed, as wellas eastern Japan far away from the central polity (Momosaki 1993). This widespread
adoption suggests to me that horses were not only the elite status symbol but also meansof carrying goods.
Because horses were not native to Japan, along with horses imported from the
Korean peninsula, equestrian specialists of breeding and raising hoses had to be invited.
Moreover, horse gears had to be produced in Japan, and local people must become
familiar with the horse gear. A considerable change in production and distribution system
must have taken place in the ﬁfth century.
This change in the ﬁfth century is particularly pronounced in eastern Japan wheretransportation was difﬁcult, and inter-regional network in the third and fourth centuries
was very limited, weak, and indirect because of more mountainous topography
characterized by larger land mass. I will refer to an example of the upstream region of
the Tenryū River, southern Nagano Prefecture, central Japan (Figure 12).
In the upstream region, the current of the Tenryū River is rapid. It is a valley between
two high mountain ridges. Water transportation by the Tenryū River between the
upstream area and downstream area near the Paciﬁc coast of central Japan has neverdeveloped to date. This region was not incorporated into an interregional network
dependent on water transportation. Because of the lack of water transportation, whichmust have prevented the acquisition of iron, people in the fourth century the upstream
Tenryū River region still continued using stone hoes for dry land farming (Matsushima[Kamimura] 1964; Yamashita 2005). These phenomena were a possible backgroundto the lack of third- and fourth-century keyhole-shaped mounded tombs in this region(Figure 13).
In the ﬁfth century, the construction of keyhole-shaped mounded tombs started in© Japanese Archaeological Association

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PROGRESS IN LAND TRANSPORTATION SYSTEM AS A FACTOR OF THE STATE FORMATION IN JAPAN

Figure 12.

Central Highland of Japan (Ina Valley)

Figure 13.

Chipped stone tools were still in use in Ina Valley in the 4th Century AD

this region suddenly (Figure 14). Large quantities of iron objects were deposited withthe dead in these mounded tombs. Moreover, a larger number of horses were buriedat the foot of these keyhole-shaped mounded tombs, than Kyushu and Kinai where thecentral Yamato polity was located (Figure 15). Stone hoes disappeared at the same time
(Figure 16). A factor that led to this drastic change in the ﬁfth century was a political© Japanese Archaeological Association

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TANAKA Yutaka

Figure 14. Keyhole-shaped Burial mound appeared in Ina Valley in the 5th Century: Mizoguchinotuka
Tumulus, Iida City, Nagano Prefecture

Figure 15. Keyhole-shaped burial mound appeared in the Ina region with horses and iron
implements in the 5th Century

introduction of horses, which initiated a new means of land transportation. This led to a
drastic increase in the use of iron, and local communities came to be organized rapidly.
The largest keyhole-shaped mounded tomb in this region was built at the foot of pass that
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PROGRESS IN LAND TRANSPORTATION SYSTEM AS A FACTOR OF THE STATE FORMATION IN JAPAN

Figure 16.

Disappearance of stone hoes in Ina Valley (the 5th and early 6th Century A.D.)

crossed a mountain ridge. This pass remained to be a strategically important location thatconnected western and eastern Japan in later historic times.
A change illustrated by the case of the upstream Tenryū River region occurred within
half a century since the practice of raising horses started in the Kinai region. This
indicates that the central Yamato polity did not intend to monopolize horses for military
purposes. Rather, it is probable that the central polity encouraged regional polities tostart raising and schooling horses, thereby creating a new, land-based interregional
network. Eastern Japan was greatly beneﬁtted from this new network, especially in termsof the acquisition of iron. A few regional communities in eastern Japan were active in
adopting horses and welcomed this new change. The aforementioned phenomena in the
upstream Tenryū River region were a reﬂection of this new change.
The introduction of horses to Japan also resulted a small but fundamental shift—a
shift in the location of a “point of change-over in transportation means.” A low
watershed in a plain became no obstacle of transportation once people rode on horses.
People no longer had to go to upstream area in order to cross small rivers. Consequently,
points of change-over in transportation means came to be formed in downstream areasand coastal regions.
This shift is clearly reﬂected in a shift in the locations of largest keyhole-shaped
mounded tombs in regions. Large keyhole-shaped mounded tombs of the central Yamato
polity in the fourth century were located in the Nara basin or the upstream on the
Yamato River. In the ﬁfth century, however, large keyhole-shaped mounded tombs of
the central polity were located in the Osaka plain, the downstream on the Yamato River,facing the Osaka Bay (Figure 17). In Kanto of eastern Japan, similarly, the locations of© Japanese Archaeological Association

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TANAKA Yutaka

Figure 17. Shifting distribution of the cluster of the largest burial mounds in the 5th century A.D.
Note that the clusters were now in the Osaka plain

Figure 18.

5th Century keyhole tumuli distribution in Kanto© Japanese Archaeological Association

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Figure 19.

Locational characteristic of the central Yamato polity

the largest keyhole-shaped mounded tombs in regions shifted from the upstream areas ofrelatively narrow rivers of gentle stream in the fourth century to the coastal regions of
the Tokyo Bay and plains facing major rivers in the ﬁfth century (Figure 18). A change
in the environment of transportation seems to have inﬂuenced the selections of seats ofthe chieﬂy authority and their locations.
In sum, the introduction of horses and subsequent spread of the practice of horseriding, initiated by the central Yamato polity, had a revolutionarily positive impact on theland transportation in the ﬁfth century, which used to limit the transportation of goods
until the fourth century. This also encouraged a drastic change in local societies that used
to heavily depend on water transportation. In particular, this brought local communities
in mountainous areas and those used to be separated by watershed much closer to eachother. All in all, a liner interregional network evolved to spatial network.
The ﬁfth century was also the time when regional differences in pottery styles
disappeared. This disappearance was particularly signiﬁcant in eastern Japan where
regional difference in pottery styles used to be very clear in the fourth century. Thissuggests to me that local polities and communities in eastern Japan willingly accepteda change, rather than maintaining regionally distinctive traditions. The central Yamato
polity that succeeded in the revolutionizing the transportation system on land must
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have gained enthusiastic support from eastern Japan, especially inland regions andregions far away from Yamato. Owing to this widespread support from local polities
and communities, the central Yamato polity gained the sole position in Japan that tiedregional polities from western Japan to eastern Japan, 1000 kilometers apart (Figure 19).

Notes
1) The Yayoi Period lasted from the seventh century B.C. or so to middle third century
A.D., and the Kofun Period from the middle third to early seventh centuries A.D.
2) In this paper, the author focuses on the case of crossing the ocean where strong tide
ﬂows and there are few islands to make stop-over. A good example is the ocean off
the coast of the Bōsō peninsula (Paciﬁc coast of Chiba prefecture). In the third or the
fourth century, A.D. Japan did not achieve the level of technology that allowed people
to cross the ocean. On the contrary, when people accumulated detailed knowledge
about the tide and several islands between the mainland and the destination, it waspossible to cross the ocean. This is evidenced by obsidian quarried in the Kōzu
Island off the coast of the Izu peninsula and transported to the mainland during the
Jomon Period. Although relatively deep sea ﬁsh are found at Jomon sites, these ﬁshsometimes travel to shallow water, and Jomon ﬁshermen probably had knowledge tocatch these ﬁsh in shallow water.
3) In this sense, it may also be necessary to pay attention to the Tsubai-Ōtsukayama
Mounded Tomb in southern Yamashiro, northern neighbor of Yamato. More than 33
Wei Chinese bronze mirrors were discovered in the burial chamber of this tomb, whichsuggest a very high social status of the buried. The Tsubai-Ōtsukayama Mounded
Tomb is situated by the Kizu River whose upstream ﬂows in the Iga Province, anothergateway to eastern Japan. I would speculate that the central polity of Yamato gained
the paramount position owing to the cooperation of inﬂuential local chiefs, including
the one buried in the Tsubai-Ōtsukayama Mounded Tomb.

References
Flannery, K.V. 1968. Archaeological systems theory and early Mesoamerica, in B.J.
Meggers (ed.) Anthropological Archaeology in the Americas: 67–87. Washington, D.C.:
Anthropological Society of Washington.
Ford, R.I. 1979. Paleoethnobotany in American Archaeology, in M.B. Schiffer (ed.)
Advances in Archaeological Method and Theory 2: 285–336. New York: Academic
Press.
© Japanese Archaeological Association

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PROGRESS IN LAND TRANSPORTATION SYSTEM AS A FACTOR OF THE STATE FORMATION IN JAPANHōjō, Y. 北條芳隆．1986. Funkyū ni Hyōji sareta Zempō-kōen-fun no Teishiki to sono Hyōka[Interpreting the Standard of the Mound Construction of Keyhole-Shaped Mounded
Tombs] 墳丘に表示された前方後円墳の定式とその評価． Kōkogaku Kenkyū 『考古学研究』32(4): 42–66.
Matsushima [Kamimura], T. 松島 透．1964. I’ida Chihō niokeru Yayoi Jidai Dasei Sekki[Yayoi Period Chipped Stone Tools in the Southern Ina Region] 飯田地方における弥生時代打製石器， in The Editorial Committee (ed.) Nihon Kōkogaku no Sho-Mondai[Various Issues in Japanese Archaeology]『日本考古学の諸問題』: 59–68. Okayama:Society for Archaeological Studies.
Momosaki, Y. 桃崎祐輔．1993. Examination of horse and cattle sacriﬁces in and by
the mounded tombs of the Kofun Period 古墳に伴う牛馬供犠の検討． KobunkaDansō 『古文化談叢』31: 1–141.
Shiraishi, T. 白石太一郎．1998. Kofun no kataru kodai-shi [Japanese ancient history as
seen from the Kofun tumulus] 『古墳の語る古代史』． Sakura: Zaidan-hojin Rekishiminzoku hakubutsukan shinko-kai.
Tamura, K. 田村浩一． 2005. Gishi Wajinden ni miru tabemono [Foods as Recorded in the
Section of Wa in the Wei-Zhi]『魏志』倭人伝にみる食べ物， in S. Kono, M. Kinoshita,
K. Tamura, T. Toizumi, & H. Horiuchi (eds.) Tabemono no Kōkogaku [Archaeology ofFood] 『食べ物の考古学』: 54–84. Tokyo: Gakuseisha.
Wada, S. 和田晴吾．1981. Mukō Shi Itsukahara Kofun no Sokuryō Chōsa yori [Reportof Mapping the Itsukahara Keyhole-Shaped Mounded Tomb, Mukō City, Kyoto
Prefecture] 向日市五塚原古墳の測量調査より， in S. Onoyama (ed.) Oryō no Hikaku
Kenkyū [A Comparative Study of Imperial Mausola]『王陵の比較研究』: 49–63. Kyoto:
Dept. of Archaeology, Kyoto University.
Yamashita, S. 山下誠一． 2005. Iida Bonchi niokeru Yayoi Jidai no Sekki [Stone Tools of
the Yayoi Period in the Iida Basin] 飯田盆地における弥生時代の石器—組成の変化と消長について—， Iida-Shi Bijutsukan Hakubutsukan Kenkyū Kiyō [Bulletin of theIida City Museum and Art Gallery]『飯田市美術博物館研究紀要』15: 153–174.

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