Jund Qinnasrin in the context of "Muslim conquest of Syria"

Bilad al-Sham (Arabic: بِلَاد الشَّام, romanized: Bilād al-Shām), often referred to as Islamic Syria or simply Syria in English-language sources, was a province of the Rashidun, Umayyad, Abbasid, and Fatimid caliphates. It roughly corresponded with the Byzantine Diocese of the East, conquered by the Muslims in 634–647. Under the Umayyads (661–750), Bilad al-Sham was the metropolitan province of the Caliphate and different localities throughout the province served as the seats of the Umayyad caliphs and princes.

Bilad al-Sham was first organized into the four ajnad (military districts; singular jund) of Dimashq (Damascus), Hims (Homs), al-Urdunn (Jordan), and Filastin (Palestine), between 637 and 640 by Caliph Umar following the Muslim conquest. The jund of Qinnasrin was created out of the northern part of Hims by caliphs Mu'awiya I (r. 661–680) or Yazid I (r. 680–683). The Jazira (Upper Mesopotamia) was made an independent province from the Mesopotamian part of Qinnasrin by Caliph Abd al-Malik in 692. In 786, the jund of al-Awasim and al-Thughur were established from the northern frontier region of Qinnasrin by Caliph Harun al-Rashid. As centralized Abbasid rule over Bilad al-Sham collapsed in the 10th century, control over the region was divided by several potentates and the ajnad only represented nominal divisions. The Abbasids and the Egypt-based Fatimid Caliphate continued to officially recognize the province and its ajnad until the Crusader invasions of the coastal regions in 1099.

Al-Jazira (Arabic: الجزيرة), also known as Jazirat Aqur or Iqlim Aqur, was a province of the Rashidun, Umayyad and Abbasid Caliphates, spanning at minimum most of Upper Mesopotamia (al-Jazira proper), divided between the districts of Diyar Bakr, Diyar Rabi'a and Diyar Mudar, and at times including Mosul, Arminiya and Adharbayjan as sub-provinces.

Following its conquest by the Muslim Arabs in 639/40, it became an administrative unit attached to the larger district of Jund Hims. It was separated from Hims during the reigns of caliphs Mu'awiya I or Yazid I and came under the jurisdiction of Jund Qinnasrin. It was made its own province in 692 by Caliph Abd al-Malik. After 702, it frequently came to span the key districts of Arminiya and Adharbayjan along the Caliphate's northern frontier, making it a super-province. The predominance of Arabs from the Qays/Mudar and Rabi'a groups made it a major recruitment pool of tribesmen for the Umayyad armies and the troops of the Jazira played a key military role under the Umayyad caliphs in the 8th century, peaking under the last Umayyad caliph, Marwan II (r. 744–750), until the toppling of the Umayyads by the Abbasids in 750.

Qays ʿAylān (Arabic: قيس عيلان), often referred to simply as Qays (Kais or Ḳays) were an Arab tribal confederation that branched from the Mudar group. The tribe may not have functioned as a unit in pre-Islamic Arabia (before 630). However, by the early Umayyad Caliphate (661-750), its constituent tribes consolidated into one of the main tribal political factions of the caliphate.

The major constituent tribes or tribal groupings of the Qays were the Ghatafan, Hawazin, Amir, Thaqif, Sulaym, Ghani, Bahila and Muharib. Many of these tribes or their clans migrated from the Arabian Peninsula and established themselves in Jund Qinnasrin, the military district of the northern region of Syria and Upper Mesopotamia, which long became their abode. From there they governed on behalf of the caliphs or rebelled against them. The power of the Qays as a unified group diminished with the rise of the Abbasid Caliphate, which did not derive its military strength solely from the Arab tribes. Nonetheless, individual Qaysi tribes remained a potent force and some migrated to North Africa and al-Andalus, where they carved out their power.