Powerful family (originally Buddhist priests) from Balkh, Khurasan, that moved west at the time of the Abbasid revolution. Produced generals, provincial governors, and tutors of young princes. Became leaders of important kuttab (bureaucrats) pressure group. Largely responsible for the coup that brought Harun al-Rashid to power in 786. Responsible for centralizing the Abbasid administration. But their power depended largely on the pleasure of the caliph, and in 803 Rashid executed leading members of the family. Conflict over the successor to Rashid, together with a lack of independent military support, led to the family's downfall.