Almoravides, a Moslem dynasty in X. Africa and Spain, which owes its origin to Abdallah ibn Yasim, who preached Islam among the Arabian tribes of northern Morocco, became the chieftain of the Al-Murabathin (the devoted, hence the word Marabout), and died in battle about A. D. 1058. Abubekr ibn Omar succeeded him, but during his absence on a warlike expedition, his lieutenant, Yusuf ibn Tash-fyn, seized the supreme power. Abubekr, on his return, finding his rival too strong, resigned the crown, and Yusuf acknowledged his forbearance by magnificent presents, which he repeated annually during Abubekr's life. Yusuf now founded the city and empire of Morocco. Invited to Spain by the Moorish prince of Seville to aid him against the Christians, he sent an embassy to Alfonso of Castile announcing his arrival in the peninsula, and summoning that monarch to an unconditional surrender, and to embrace Mohammedanism. A desperate battle was fought in the plains of Zalaca in 1086, in which the Christians were worsted.

Yusuf, however, retired, but the following year returned, conquered the Moorish kings in detail, and, having proclaimed his son as his successor, retired to Morocco, where he died in 1106. About 40 years later the dynasty of the Almo-ravides was overthrown by the Almohades.