In the lands of the Caliphate, especially in Babylonia (Irak), at that time the center of Jewish life, the Jews gradually lost the favorable position which they had hitherto enjoyed, although the intolerance of the Mahometan rulers was mild compared with that of the Christian princes. In the East, too, they were the prey of caprice, for the Caliphs resigned their power in favor of the vizirs, and thus deprived themselves of all power. The Caliphs after Al-Mamun became more and more the tools of ambitious and greedy ministers and generals, and the Oriental Jews frequently had to buy the favor of these ephemeral lords at a high price. The Caliph Al-Mutavakkil, Al-Mamun's third successor, renewed the laws of Omar against the Jews, Christians, and Magi, and compelled them to wear a characteristic dress, a yellow scarf over their dress, and a thick cord instead of a girdle. He, moreover, changed the synagogues and churches into mosques, and forbade the Mahometans to teach Jews and Christians, or to admit them to offices (849-856). A tenth part of their property had to be given to the Caliph; they were forbidden to ride upon horses, and were allowed to make use only of asses and mules (853-854). The Exilarchs had lost a part of their power, when Al-Mamun decreed that they should no longer be officially recognized and supported, and they lost still more through the fanaticism of Al-Mutavakkil. By and by they ceased to be officials of the state, invested with certain powers, and had to content themselves with the position which the Jewish communities gave them out of respect for old and dear memories. As the Exilarchate declined, the respect increased for the school of Pumbeditha, because it was near the capital of the Bagdad Caliphate, whose Jewish community of influential men came under its jurisdiction. Pumbeditha now rose from the subordinate position into which it had been forced. It put itself on an equal footing with the sister academy of Sora, and its presidents likewise assumed the title of Gaon. It next made itself independent of the Exilarchate. Formerly the head of the school and the faculty of Pumbeditha had to go once a year to pay homage to the Exilarch, but now, if the Exilarch wished to hold a public assembly, he had to repair to Pumbeditha. This was probably brought about by the chief of the school, Paltoi ben Abayi (842-858), who heads the list of important Geonim, and who was noted for his free use of the Cherem (Excommunication). Dissensions about the succession to the Gaonate were not wanting during this period, although the Exilarchs could not make their influence felt.