Southward Mande migration and the Muslim revolution in the Futa Jallon push populations from the southwestern Sudan into the upper Guinea coast (modern Sierra Leone and Liberia, and the coast of present-day Guinea). These migrations lead to the diffusion of systems of belief and aesthetic motifs. Prospering from the trans-Saharan gold trade, the Akan kingdoms (in modern Ghana) compete for regional dominance. The kingdom of Asante, under ruler Osei Tutu, prevails and promotes the growth and dissemination of courtly arts. In what is now western Nigeria, the Yoruba state of Oyo employs its formidable cavalry to gain economic hegemony over its neighbors, including the nascent kingdom of Dahomey to the west. Finally, the kingdom of Benin suffers a nearly century-long period of political turmoil and economic depression, but reemerges in the eighteenth century as an important trading power and center of artistic production.