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 orders from Oyo were strictly followed, and access to local markets was provided to Oyo merchants. The Oyo often demanded tribute in slaves. The tributary sometimes made war on other peoples to capture slaves for this. Oyo punished disobedience by wholesale slaughter of the community, as it accomplished in Allada in 1698. The Oyo Empire developed a highly sophisticated political structure to govern its territorial domains. Scholars have not determined how much of this structure existed prior to the Nupe invasion. Some of Oyo's institutions are clearly derivative of early accomplishments in Ife. After reemerging from exile in the early