Muhammad was born in 824/5 (AH 209).[1] He was the son of Abdallah ibn Tahir al-Khurasani, who after a distinguished military career became military governor (wali al-harb wa'l-shurta) of Baghdad, before going on to rule a vast viceroyalty in the East, comprising central and eastern Iran, from 830 to 845; according to C.E. Bosworth, he was "perhaps the greatest of the Tahirids". Baghdad and the family's interests in Iraq remained in the hands of his cousin, Ishaq ibn Ibrahim and his heirs.[2][3] In the East, Abdallah was succeeded by his son Tahir, but in Iraq, the family's position was far less stable, as the Tahirids there quarrelled among themselves.[4] As a result, in 851 the Caliph al-Mutawakkil called Muhammad ibn Abadallah from Khurasan to Iraq, where he assumed the governorships of Baghdad, the Sawad and Fars, while according to the 10th-century Egyptian scholar al-Shabushti, he also served as the caliphs' chamberlain (hajib).[5]