It was from one of Mali's former conquests, the kingdom of Gao, that the last major empire of the western Sudan emerged. Although the city of Gao had been occupied by a Songhai dynasty prior to being conquered by Mansa Musa's forces in 1325, it was not until much later that the Songhai empire emerged. It began to rise in 1464 when Sonni cAli Ber came to power. Sonni cAli conquered much of the weakening Mali empire's territory as well as Timbuktu, famous for its Islamic universities and the pivotal trading city of Jenne. Following Sonni cAli's death, Muslim factions rebelled against his successor and installed Askia Muhammad (formerly Muhammad Ture) as the first ruler of the Askia dynasty (14921592). Under the Askias, the Songhai empire reached its zenith, Timbuktu and Jenne flourished as centers of Islamic learning, and Islam was actively promoted.