 The slave trade also encouraged the formation of states such as the Asante Empire, Bambara Empire and Dahomey, whose economic activities include but not limited to exchanging slaves for European firearms.In the early 19th century, a series of Fulani reformist jihads swept across Western Africa.The most notable include Usman dan Fodio's Fulani Empire, which replaced the Hausa city-states, Seku Amadu's Massina Empire, which defeated the Bambara, and El Hadj Umar Tall's Toucouleur Empire, which briefly conquered much of modern-day Mali.