In 1086, Yusuf ibn-Tashufin, an African, defeated Alfonso VI of Castile in a battle at Zallaca, and thus initiated the Almoravid occupation of the southern half of the Iberian Peninsula. With the conquest of Al-Andalus (Moslem Spain), the Almoravid Empire extended from the basin of the Senegal River in Africa to the Tagus River in Europe. The reign of the Almoravids in Spain was, however, shortlived, for the loss of Saragossa in 1118 ushered in a period of decline which culminated in a series of popular rebellions in 1144, and the defeat of the African Moslems in 1145. Opinion about the Almoravid rule is varied: some scholars, including several of the foremost Hispanic and French Arabists, bemoan the Africanization of Spain, while others, primarily Arab and Jewish writers, speak of a Golden Age of letters under the Almoravids, who unified Moslem Spain and imposed order on the warring Arab caliphs. Much of the controversy surrounding the Almoravids is centered in the person of their leader, Yusuf ibn-Tashufin, who was vividly portrayed in Arab, Latin and Castilian chronicles of the twelfth and thirteenth centuries, and who figured prominently in Castilian epic poetry, including the twelfth-century Poema de Mio Cid, as well as in Galician-Portuguese lyric poetry, such as the Cantigas of Alfonso X of Castile. Much of the information about Yusuf is distorted, depending upon the religious or political views of the chronicler; thus, Spanish Catholics tended to minimize the importance of Yusuf, emphasizing, instead, his cruelty, intolerance, alleged arrogance or stupidity, and his persecution of non-Moslems; while Moslem writers exalted him as the saviour of Al-Andalus, a tolerant, deeply religious and pious man. It is difficult in the case of Yusuf to separate historical truth from literary fantasy, for a host of legends, humorous anecdotes and bogus letters were later attributed to the African conqueror; the truth was further distorted by poets, who were more concerned with dramatic effect and literary style than with historic fact.