The position of the Jews during the five centuries of the domination of the Abbassid Califs (750-1258) differed from that under their predecessors, the Ommiads, as the Abassids were troubled by no fears that Jewish influence would check the spread of Islam. The foundation of Bagdad by Al-Mansur (the second Abbassid Calif) brought the seat of Moslem government in close proximity to the two centers of Jewish spiritual life, Sura and Pumbedita. Contrary to the policy of the earlier califs, who removed the Jews to the extreme borders of the empire, Bagdad was allowed to retain a Jewish community.
It is not to be inferred that under the Abbassids the Jews enjoyed continual peace. They suffered not only from the incessant civil wars and revolutions, but ancient and forgotten restrictions and humiliations were occasionally renewed. Harun-al-Raschid (786-809) revived Omar's regulation ordering non-Moslems to wear distinguishing marks on their clothing (see Badge), and forbidding them to ride horses. Although these regulations fell into disuse under the next califs, they were renewed with great vigor under the reactionary Al-Mutawakkil (850), who caused many synagogues to be converted into mosques, and levied tithes on the houses of non-Moslems. Yet under Al-Mutadhid (892-902) many Jews were employed in the service of the state.
The decline of the temporal power of the califs, which occurred before the end of the tenth century, could not fail to affect the fate of the Jews in the eastern portions of the empire, because the viziers, and afterward the sultans, were too much occupied with other cares to trouble themselves about the Jews (see Crusades). Bagdad, especially, suffered heavily; yet in the middle of the twelfth century its Jewish community numbered one thousand families, while that of Mosul was even larger. The calif Mohammed al-Muktafi (1136-60) made Bagdad the seat of the exilarch, who became the recognized head of nearly all the Jews of the Abbassid empire. This favorable state of things was due mainly to the tolerant reign of the Seljuk sultans, especially Zengi, Nur-ed-Din, and Saladin (see also Alroy).