these two academies in order that the promise might be fulfilled, that 'the word of God should never depart from Israel's mouth (Isa. lix. 21). The periods of Jewish history immediately following the close of the Talmud are designated according to the titles of the teachers at Sura and Pumbedita; thus we have the time of the Geonim and that of the Saboraim. The Saboraim were the scholars whose diligent hands completed the Talmud and the first great Talmudic commentaries in the first third of the 6th century. The two academies among others, and the Jewish community they led, lasted until the middle of the 11th century, Pumbedita faded after its chief rabbi was murdered in 1038, and Sura faded soon after. Which ended for centuries the great scholarly reputation given to Babylonian Jews, as the center of Jewish thought. Islamic Arab period The first legal expression of Islam toward the Jews, Christians, and Zoroastrians after the conquests of the 630s were the poll-tax ("jizyah"), the tax upon real estate ("kharaj") was instituted. The first caliph, Abu Bakr, sent the famous warrior Khalid bin Al-Waleed against Iraq; and a Jew, by name Ka'ab al-Aḥbar, is said to have fortified the general with prophecies of success. The Jews may have favored the advance of the Arabs, from whom they could expect mild treatment. Some such services it must have been that secured for the exilarch Bostanai the favor of Umar I, who awarded to him for a wife the daughter of the conquered Sasanian Chosroes II as Theophanes and Abraham Zacuto narrate. Jewish records, as, for instance, "Seder ha-Dorot," contain a Bostanai legend which has many features in common with the account of the hero Mar Zutra II, already mentioned. The account, at all events, reveals that Bostanai, the founder of the succeeding exilarch dynasty, was a man of prominence, who received from the victorious Arab general certain high privileges, such as the right to wear a signet ring, a privilege otherwise limited to Muslims. Omar and Othman were followed by Ali (656), with whom the Jews of Babylonia sided as against his rival Mu'awiyah. A Jewish preacher, Abdallah ibn Saba, of southern Arabia, who had embraced Islam, held forth in support of his new religion, expounded Mohammed's appearance in a Jewish sense. Ali made Kufa, in Iraq, his capital, and it was there that Jews expelled from the Arabian Peninsula