Thabit was a native of Khurasan,[1] and the grandson of Malik ibn al-Haytham al-Khuza'i, an early Abbasid follower and military leader.
[2] He was appointed as governor of the Syrian thughur (essentially comprising Cilicia, with Tarsus as its capital) in the last year of the reign of Harun al-Rashid (808/9).
[3][4] He organized a prisoner exchange with the Byzantines at Podandos in 808,[5][6] but also led a series of raiding expeditions (sawa'if) against them.
[3] In one of these however, in August 812, he suffered a heavy defeat at the hands of Leo the Armenian, losing 2,000 men.
810, with the outbreak of a civil war between al-Amin and his brother al-Ma'mun, Thabit, like many other provincial governors and magnates, was able to assume virtually independent control of his province.