Al - ' Awasim The al - ' Awāṣim ( , " defences , fortifications " ; sing . " al - ' āṣimah " , " protectress " ) was the Arabic term used to refer to the Muslim side of the frontier zone between the Byzantine Empire and the Umayyad and Abbasid Caliphates in Cilicia , northern Syria and Upper Mesopotamia . It was established in the early 8th century , once the first wave of the Muslim conquests ebbed , and lasted until the mid - 10th century , when it was overrun by the Byzantine advance . It comprised the forward marches , comprising a chain of fortified strongholds , known as the al - thughūr ( ; sing . , " al - thagr " , " cleft , opening " ) , and the rear or inner regions of the frontier zone , which was known as the " al - ' awāṣim " proper . On the Byzantine side , the Muslim marches were mirrored by the institution of the " kleisourai " districts and the " akritai " border guards . The term " thughūr " was also used in the marches of al - Andalus and Mawara al - Nahr , and survived in historical parlance , to be revived by the Egyptian Mamluks in the 14th century , when the areas traditionally comprising the " ' awāṣim " and " thughūr " in northern Syria and the northern Euphrates region came under their control . Arab – Byzantine frontier zone . Creation of the frontier zone . Already from late 630s , after the rapid Muslim conquest of Syria , a wide zone , unclaimed by either Byzantines or Arabs and virtually deserted ( known in Arabic as " al - Ḍawāḥī " , " the outer lands " and in Greek as , " ta akra " , " the extremities " ) emerged between the two powers in Cilicia , along the southern approaches of the Taurus and Anti - Taurus mountain ranges , leaving the Anatolian plateau in Byzantine hands . Both Emperor Heraclius ( r . 610 – 641 ) and the Caliph ' Umar ( r . 634 – 644 ) pursued a strategy of destruction within this zone , trying to transform it into an effective barrier between their realms . Nevertheless , the ultimate aim of the caliphs remained the outright conquest of Byzantium , as they had done with its provinces in Syria , Egypt and North Africa , and it was only the failure of the Second Arab Siege of Constantinople in 717 – 718 that forced a revision of this strategic objective : although raids into Anatolia continued , the goal of conquest was abandoned , and the border between the two powers began to acquire more or less permanent features . For the next two centuries , border fortresses might change hands between Byzantines and Arabs , but the basic outline of the Arab – Byzantine border remained essentially unaltered . Thus the term " al - thughūr " , which initially meant " fissures , clefts " ( cf . their Greek name , " ta Stomia " , " the mouths / openings " ) and designated the actual borderlands , came to mean " boundaries " , employed in phrases like " Thughūr al - Islām " , " boundary of Islam " or " Thughūr al - Rūmīya " , " boundary of the Romans " . This process was marked by a gradual consolidation of the previously deserted zone and its transformation into a settled and fortified borderland , especially after the Byzantines abandoned Cilicia during the reign of Caliph Abd al - Malik ( r . 685 – 705 ) . The Muslims began to move into the area , reoccupying and repairing the abandoned towns and forts . The process began under the Umayyads , but intensified under the first Abbasids , especially during the rule of Harun al - Rashid ( r . 786 – 809 ) . Thus a line of forts was gradually established , stretching from Tarsus ( Ar . Ṭarsūs ) on the Mediterranean coast to Malatya ( Ar . Malaṭiyā , Gr . Melitene ) and Kamacha ( Ar . Ḥiṣn Kamkh ) on the upper course of the Euphrates . These were located at strategic choke points , located at the intersections of major roads or at the mouths of important passes . Administrative organization and settlements . The entire frontier zone was initially part of the " jund " ( one of the military administrative divisions into which Muslim Syria was divided ) of Homs . After 680 it formed part of the new " jund " of Qinnasrin ( Gr . Chalkis ) , until Harun al - Rashid established a separate jund al - ' Awāṣim in 786 , covering the entire region from the Byzantine border in the north and west to the Euphrates in the east and a line running south of Antioch ( Ar . Anṭākiya ) , Aleppo ( Ar . Ḥalab , Gr . Berroia ) and Manbij ( Gr . Hierapolis ) . Manbij and later Antioch were the new province ' s capitals . The " al - ' Awāṣim " proper served as the second defensive line behind the " Thughūr " , stretching across northern Syria and comprising the towns of Baghras , Bayās , Dulūk ( Gr . Doliche or Telouch , modern Gaziantep ) , Alexandretta ( Ar . Iskandarīya ) , Cyrrhus ( Ar . Ķūrus ) , Ra ' bān and Tīzīn . The " Thughūr " , the actual frontier zone , was divided into the Syrian ( " Thughūr al - Sha ' mīya " ) and the Upper Mesopotamian ( " Thughūr al - Jazīrīya " ) sectors , roughly separated by the Amanus mountains . There was no overall governor or a capital , although Tarsus and Malatya were the most important towns in Cilicia and the Mesopotamian sector respectively . The towns of the " Thughūr " came variously under the administrative control of the " jund al - ' Awāṣim " or functioned as separate districts . The situation is complicated by the fact that by the 10th century , the terms " Thughūr " and " al - ' Awāṣim " were often used interchangeably . In addition , from the early 10th century , with the Byzantine advance into Armenia , the frontier around Diyār Bakr became a third sector , " Thughūr al - Bakrīya " . In the Cilician sector , Mopsuestia ( Ar . al - Maṣṣīṣa ) was the first city to be re - occupied and garrisoned , already under the Umayyads , who settled 300 soldiers there in 703 , a number raised under the first Abbasids to some 4 , 000 . Adana followed in 758 – 760 , and Tarsus in 787 / 788 . Tarsus quickly became the largest settlement in the region and the Arabs ' most important base of operations against the Byzantines , counting between 4 , 000 and 5 , 000 troops in its garrison . Other important fortresses in Cilicia , which however were little more than military outposts , were ' Ayn Zarba ( Gr . Anazarbus ) , al - Hārūniya , founded by Harun al - Rashid , Tall Gubair and al - Kanīsat al - Sawdā . These were complemented by smaller forts dotted across the Cilician plain , holding smaller garrisons of a dozen or so men . In the more mountainous terrain of the Upper Mesopotamian frontier zone , the main strongholds were located in the fertile parts of relatively isolated valleys , controlling the entrances of passes over the mountains : Mar ' ash ( Gr . Germanikeia ) , rebuilt already under Muawiyah I ( r . 661 – 680 ) and again under Harun al - Rashid , al - Ḥadath ( Gr . Adata ) , likewise refortified by the first Abbasid caliphs and provided with 4 , 000 troops , and Malatya , which had been colonized by the Umayyads , destroyed by the Byzantines and rebuilt again and likewise garrisoned with 4 , 000 men in 757 / 758 . Further fortresses of lesser importance in the Mesopotamian sector were Salaghus , Kaisum , Ḥiṣn Zibaṭra ( Gr . Zapetra / Sozopetra ) , Sumaisaṭ ( Gr . Samosata ) , Ḥiṣn Qalawdhiya and Ḥiṣn Ziyad . Some of the northern fortresses of the " al - ' Awāṣim " province , like Dulūk or Cyrrhus , were also sometimes included in it . Further north , the relatively isolated fortress towns of Qālīqalā ( Gr . Theodosiopolis , modern Erzurum ) and Kamacha formed the northern - most outposts of Muslim rule . The " Thughūr al - Bakrīya " included , according to Qudama ibn Ja ' far , Sumaisaṭ , Ḥānī , Malikyan , Gamah , Ḥaurān and al - Kilis . The caliphs repopulated the area by bringing in colonists and regular soldiers from Syria but also Persia ns , Slavs , Arab Christians , and people from the eastern edges of the Muslim world : settlers from Khurasan , the Turkic Sayābija tribe or Jatt s ( Ar . Zuṭṭ ) from India . The regular troops stationed there were favoured with lower taxes ( the tithe or " ' ushr " instead of the " kharāj " land tax ) , higher pay and small land grants ( " qaṭā ' i " ) . In early Abbasid times these troops numbered some 25 , 000 , half of them drawn from Khurasan and the rest from Syria and Upper Mesopotamia . They were complemented by volunteers , drawn by the religious motivation of " jihad " against the Byzantines but often paid a salary by the state as well . All this entailed a heavy financial burden on the Abbasid state . Under Harun al - Rashid , taxation from the Cilician sector brought in 100 , 000 gold dinar s , which were all spent for public works , salaries , espionage etc . In addition , the costs of cross - border expeditions typically ranged between 200 , 000 – 300 , 000 dinars . The Mesopotamian sector ' s revenue amounted to some 70 , 000 dinars , to which the central government added 120 , 000 – 170 , 000 dinars each year for the upkeep of the fortifications and the salary of the frontier troops . Military operations . By the 9th century , the Arab raiding expeditions launched against Byzantium from the frontier zone had gradually assumed an almost ritual character and were strictly organized . According to Qudama ibn Ja ' far , the conventional pattern of Arab incursions included a first expedition in spring ( 10 May – 10 June ) , when horses could find abundant fodder , followed after about a month ' s rest by a summer raid ( 10 July – 8 September ) , usually the main campaign of the year , and sometimes by a winter raid in February – March . The importance of these raids is summarized by Islamic scholar Hugh N . Kennedy : " the " ṣā ’ ifa " ( summer raid ) was as much a part of the symbolic and ritual functions of the Caliph as was organising and providing leadership for the annual " hajj " to Mecca " . The frontier zone was fiercely contested between the Arabs and the Byzantines . Raids and counter - raids were a permanent fixture of this type of warfare . Forts on either side of the notional frontier were captured and razed , or sometimes occupied , but never for long . As a result , the region was often depopulated , necessitating repeated resettlement . There is nevertheless evidence of some prosperity , based on agriculture and commerce , especially during the second half of the 9th century , when the borderlands became a node in a commercial route linking Basra with northern Syria and even Constantinople . As the 9th century progressed , the Abbasids ' control over the " Thughūr " devolved to semi - independent border emirates , chiefly Tarsus , Malatya and Qālīqalā . After 842 , with the decline of Abbasid power , they were left largely to fend on their own against a resurgent Byzantium . The Battle of Lalakaon in 863 broke the power of Malatya , altering the balance of power in the region , and began a gradual Byzantine encroachment on the Arab borderlands . With the onset of a prolonged period of crisis in the Abbasid Caliphate after 928 , control of the Muslim frontier cities shifted to the Ikhshidid and Hamdanid dynasties . Under the leadership of John Kourkouas , the Byzantines broke through and conquered Malatya and most of the Mesopotamian sector of the " Thughūr " in the 930s . Although the Hamdanid emir of Aleppo , Sayf al - Dawla ( r . 946 – 967 ) managed to stem the tide , his success was only temporary : in 964 – 965 , the Emperor Nikephoros II Phokas ( r . 963 – 969 ) captured Cilicia , followed soon after by Antioch , while Aleppo became a tributary state . Mamluk – Turkmen frontier zone . After their conquest of Syria , the Egyptian Mamluks re - established the " al - thughūr wa - l - ' awāṣim " as a defensive zone to shield Syria from the Turkoman states of Asia Minor and the Caucasus , including at a later stage the Ottoman Empire . Like the earlier model , the " thughūr " were divided into a Syrian and a Mesopotamian march , as well as a rear zone along northern Syria . The Mamluks entrusted the defence of the Syrian / Cilician march to the client Turkmen principality of the Ramadanids , while the Dulkadirid principality fulfilled the same role in the Mesopotamian " thughūr " . To safeguard their control of the frontier zone , and to keep the two client beyliks separated and under control , the Mamluks also retained garrisons in seven strategically important sites : Tarsus , Ayas , Serfendikar , Sis , Darende , Malatya and Divriği . Ahmad al - Qalqashandi gives the subdivisions ( " niyābāt " ) of the Mamluk " thughūr " as follows : eight for the Syrian sector ( Malatya , Divriği , Darende , Elbistan , Ayas , Tarsus and Adana , Serfendikar and Sis ) and three on the Euphrates sector ( al - Bira , Qal ' at Ja ' bar and al - Ruha ) .