[1] By early 749, the anti-Umayyad uprising that had begun under Abu Muslim in Khurasan had prevailed in the eastern lands of the Caliphate, and the Khurasani armies swept west across Persia to the borders of Iraq.

In October 749, al-Saffah was proclaimed Caliph at Kufa, and quickly gained the acceptance of Abu Muslim and the Kufans, thereby forestalling an Alid bid for control of the revolution.

To cement Abbasid control, al-Saffah now appointed members of his own family to command the armies: his brother, the future al-Mansur, was sent to lead the Siege of Wasit, while Abd Allah was sent to confront the Umayyad caliph Marwan II (r. 744–750) in the Jazira.

[4] This harsh suppression, and the depredations of the victorious Khurasani soldiers, soon provoked an uprising by the Syrian tribes, led by the governor of Jund Qinnasrin, Abu'l-Ward ibn al-Kawthar.

[8] Despite the recurrence of pro-Umayyad revolts in the Jazira, over the next few years Abd Allah was apparently able to secure the loyalty of the Syrian tribal nobility, and the province remained mostly calm.

[1][10][11] The veracity of Abd Allah's claim and the level of legitimacy he enjoyed vis-à-vis al-Mansur is difficult to assess following the prevalence of hostile traditions after his defeat, but, as P. Cobb comments, "what all accounts agree on is that the succession to al-Saffah was not solidly secured before his death", and there are indications that Abd Allah "had portrayed himself as an obvious successor [...] in the few years prior to al-Saffah's death.

"[9] Abd Allah enjoyed broad support in Syria, both by the native Syro-Jaziran troops and the Syrian elites who sought to regain the privileged position they had held under the Umayyads, as well as the Khurasani soldiers he had commanded during the Revolution.

In the words of Hugh N. Kennedy, Abd Allah "suspected treachery all round and fled before the battle really developed", seeking refuge in Basra, where another brother of his, Sulayman, was governor.