It is believed by some that Ali, the nephew and son-in-law of the prophet Muhammad was supposed to be his successor. Ali's follower are known as the Alids. The Alids became the figure-heads of certain movements within Islam which ultimately aimed at undermining its foundations and gave it an entirely new appearance. At the dawn of the Arab empires, many non-Arabs converted to Islam. However, many of these peoples still held onto their old beliefs, which caused the formation of a large number of sects with a mixture of extremely heterogeneous elements. The Caliphs hated these sects. Under these circumstances, the Alids, who have been wronged, became the natural center of all dissatisfaction that had been rapidly accumulating in Islam. The heterodox sects which arose were thus driven towards Shi’ism.