Al-Ḍaḥḥāk ibn Qays al-Shaybānī (Arabic: الضحاك بن قيس الشيباني) was the leader of a widespread but unsuccessful Kharijite rebellion in Iraq against the Umayyad Caliph Marwan II from 745 until his death in battle in 746.
In August however Ibn Umar gave himself up, and, in an unprecedented act for a member of the Umayyad dynasty and of the Prophet's own Quraysh tribe, did homage to Dahhak, who was neither and who had by now been declared caliph by his followers.
[2][3] Kufa was now occupied by Dahhak's forces and became his seat, while Ibn Umar was named governor of Wasit, eastern Iraq and western Persia.
Dahhak's generosity in rewarding his followers, as well as the attractiveness of Kharijite doctrine quickly swelled his ranks further, until his army is said to have reached 120,000 men.
Among others, the famed general Sulayman, a son of Caliph Hisham ibn Abd al-Malik and opponent of Marwan, sought refuge with him.