As senior members of the privileged Khurasaniyya, the Khurasani army that formed the main pillar of the new regime, Malik's family enjoyed access to positions of power.
[5][6] Consequently, Abdallah's power diminished when Harun rose to the throne and during the period of the Barmakids' dominance of the government,[5] although he served as governor of Mosul in 789–791.
[4] After the fall of the Barmakid family in early 803, Abdallah once again assumed high offices: he served as commander of Harun's shurta, and in 805 became governor of Tabaristan, Hamadan, and other western Iranian provinces.
In the subsequent civil war between al-Ma'mun and his half-brother, Caliph al-Amin (r. 809–813), he remained largely on the sidelines at Marw.
He was one of several military leaders who refused to head al-Ma'mun's government, a post which eventually fell to Fadl ibn Sahl.