After the decline of Mali, the kingdom of Gao reasserted itelf as the major kingdom in the Sahel. A Songhay kingdom in the region of Gao had existed since the eleventh century AD, but it had come under the control of Mali in 1325. In the late fourteenth century, Gao reasserted itself with the Sunni dynasty. Songhay would not fully eclipse Mali until the reign of the Sunni king, Sonni Ali, who reigned from 1464-1492.
Sonni Ali aggressively turned the kingdom of Gao into an empire, the Songhay empire. Sonni Ali based his military on a cavalry and a highly mobile fleet of ships. With this military, he conquered the cities of Timbuctu and Jenné, the major cities of the Sahel. The Berbers, who had always played such a crucial role in the downfall of Sahelian kingdoms, were pushed far north.
Sonni Ali was succeeded by Askia Muhammad Touré (1493-1528), who established a new dynasty, the Askia. Muhammad Touré continued Sonni Ali's imperial expansion by seizing the important Saharan oases and conquering Mali itself. From there he conquered Hausaland. In addition, Muhammad Touré further centralized the government by creating a large and elaborate bureaucracy to oversee his extensive empire. He was also the first to standardize weights, measures, and currency, so culture throughout the Songhay began to homogenize. Muhammad Touré was also a fervent Muslim; he replaced native Songhay administrators with Arab Muslims in order to Islamicize Songhay society. He also appointed Muslim judges, called qadis , to run the legal system under Islamic legal principles. These programs of conquest, centralization, and standardization were the most ambitious and far-reaching in sub-Saharan history until the colonization of the continent by Europeans. Songhay reached its greatest territorial expansion under Askia Daud (1549-1582), when the empire stretched all the way to Cameroon. With literally several thousand cultures under its control, Songhay was the largest empire in African history.
While the urban centers were dominated by Islam and Islamic culture, the non-urban areas were not Islamic. The large majority of the Songhay peoplearound 97%followed traditional African religions.
Songhay, however, had gotten too large; it encompassed too much territory to control. After the reign of Askia Duad, subject peoples began to revolt even though Songhay had an army of over 35,000 soldiers. The first major region to go was Hausaland; then Maghreb (Morocco) rebelled and gained control over crucial gold mines. The Moroccans defeated Songhay in 1591 and the empire quickly collapsed. In 1612, the cities of Songhay fell into anarchy and the greatest empire of African history came to a sudden close.