[1][2] According to al-Kindi, he was initially an unimportant member of the so-called abna’ al-dawla, the Khurasani troops that formed the mainstay of the Abbasid regime.
He came to Egypt in 799 in the retinue of al-Layth ibn al-Fadl, and soon rose to a position of influence within the local abna’.
[3] The early years of the 9th century were a time of turmoil for Egypt, where the old-established elites of the original Arab settlers of Fustat losing power to the abna’ and their rivals, the Yemeni tribes of northern Egypt, grouped around Abd al-Aziz ibn al-Wazir al-Jarawi.
Taking advantage of the collapse of Abbasid central authority due to the civil war between al-Amin and al-Ma'mun, Abd al-Aziz and al-Sari, with their respective factions, engaged in a vicious struggle for control of the province that by 813 had effectively divided Egypt between them, with the Yemenis holding the north and al-Sari Fustat and the south.
[4] His first tenure as governor of Egypt was short, lasting from April to September 816, but he was reappointed to the post in March 817 and held it until his death in November 820.