The Mali Empire later formed on the upper Niger River, and reached the height of power in the 14th century. Under the Mali Empire, the ancient cities of Djenné and Timbuktu were centers of both trade and Islamic learning. The empire later declined as a result of internal intrigue, ultimately being supplanted by the Songhai Empire. The Songhai people originated in current northwestern Nigeria. The Songhai had long been a major power in West Africa subject to the Mali Empire's rule.