Not long after his arrival in Egypt in 1167 C.E., Maimonides was appointed physician to the ruler of the country and his entourage. Maimonides was sought out by the Jewish community not only for medical treatment, but also for guidance and help in its private and communal affairs. Such was his reputation that a request for advice soon came to him from Jacob ben Nathanel al-Fayyumi on behalf of the Jews of Yemen. There too a fanatical Muslim movement was threatening the existence of the Jewish community. The movement had been started in 1150 by the Shi'ite Ali ibn Mahdi and was now attempting to force the conversion of all non-Moslems under his son 'Abd al-Nabi' ibn Mahdi.
Jacob raised several issues in his request for advice. What was the significance of the community's suffering? How should they respond to a convert who had become a missionary for Islam and claimed that the Torah itself confirmed the prophethood of Muhammad? What should they make of the claim of another individual to be the Messiah, come to rescue them from their persecutors? Could the date of the Messiah's coming be predicted by astrology?
Maimonides gave his ruling on all these questions in his Epistle to Yemen of 1172, so phrasing his answers that the community might be encouraged to avoid succumbing either to the oppressor or to messianic delusions.