In al-Tabari's chronicle, Isa first appears in 813, near the end of civil war between the rival caliphs al-Amin (r. 809–813) and al-Ma'mun (r. 813–833), as one of the individuals in al-Amin's entourage.[1] Following al-Amin's execution in September 813, Isa entered into the service of al-Hasan ibn Sahl,[2] who had been appointed by al-Ma'mun as governor of Baghdad, and over the next several years he participated in the struggle to maintain al-Ma'mun's authority in the central lands of the caliphate.[3]