Umar was introduced, which protected the Jews but also established them as inferior. Since the 11th century, there have been instances of pogroms against Jews. Examples include the 1066 Granada massacre, the razing of the entire Jewish quarter in the Andalucian city of Granada. In North Africa, there were cases of violence against Jews in the Middle Ages, and in other Arab lands including Egypt, Syria and Yemen. Beginning in the 15th century, the Moroccan Jewish population was confined to segregated quarters known as mellahs. In cities, these were surrounded by walls and a fortified gateway. Rural mellahs, however, were separate villages inhabited solely by Jews. The Almohads, who had taken control of much of Islamic Iberia by 1172, were far more fundamentalist in outlook than the Almoravides, and they treated the dhimmis harshly. Jews and Christians were expelled from Morocco and Islamic Spain. Faced with the choice of either death or conversion, some Jews, such as the family of Maimonides, fled south and east to more tolerant Muslim lands, while others went northward to settle in the growing Christian kingdoms. In 1465, a mob enraged by stories about the behavior of a Jewish vizier killed many of the Jews and the Sultan himself. The community was temporarily converted but soon reverted to Judaism. Historian Mark R. Cohen proposes a comparative approach to understanding Jewish life under Islamic rule, noting that Jews in Islamic lands often experienced less physical violence than Jews under Western Christendom. He posits that Muslims considered Jews less theologically threatening than Christians did, suggesting that the Christians wanted to establish a separate religious identity from Judaism, from which their faith split and diverged. According to him, instances of persecution were occasional, more the exception than the rule, and claims of systemic persecution at the hands of Muslim rulers are myths created to bolster political propaganda. The situation where Jews in the Muslim world both enjoyed cultural and economic prosperity at times, but were widely persecuted there at other times, was summarised by G. E. Von Grunebaum: It would not be difficult to put together the names of a very sizable number of Jewish subjects or citizens of the Islamic area who have attained to high rank, to power, to great financial influence, to significant and recognized intellectual attainment; and the same could be done for Christians. But it would again not be difficult to compile a