History of Nigeria city-states. A state council (the "Oyo Mesi") named the "Alaafin" (king) and acted as a check on his authority. Their capital city was situated about 100 km north of present-day Oyo. Unlike the forest-bound Yoruba kingdoms, Oyo was in the savanna and drew its military strength from its cavalry forces, which established hegemony over the adjacent Nupe and the Borgu kingdoms and thereby developed trade routes farther to the north. The Benin Empire (1440–1897; called "Bini" by locals) was a pre-colonial African state in what is now modern Nigeria. It should not be confused with the modern-day country called Benin,
Oyo Empire became the southern emporium of the Trans-Saharan trade. Exchanges were made in salt, leather, horses, kola nuts, ivory, cloth and slaves. The Yoruba of metropolitan Oyo were also highly skilled in craft making and iron work. Aside from taxes on trade products coming in and out of the empire, Oyo also became wealthy off the taxes imposed on its tributaries. Taxes on the kingdom of Dahomey alone brought in an amount estimated at 638 thousand dollars a year. By 1680, the Oyo Empire spanned over 150,000 square kilometers. It reached the height of its power in the 18th century. And