History of Africa usually governed by an "oba" and an "iwarefa", a council of chiefs who advised the "oba." by the 18th century, the Yoruba city-states formed a loose confederation, with the "Oni" of Ife as the head and Ife as the capital. As time went on, the individual city-states became more powerful with their "obas" assuming more powerful spiritual positions and diluting the authority of the "Oni" of Ife. Rivalry became intense among the city-states. The Oyo Empire rose in the 16th century. The Oyo state had been conquered in 1550 by the kingdom of Nupe, which was in possession of cavalry,
Oyo Empire 17th century, Oyo took on a noticeably more militant character. The influence of an aggressive Yoruba culture is exemplified in the standards placed on the oba (king) and the roles of his council. The oba (meaning 'king' in the Yoruba language) at Oyo, who was referred to as the Alaafin of Oyo (Alaafin means 'owner of the palace' in Yoruba), was the head of the empire and supreme overlord of the people. He was responsible for keeping tributaries safe from attack, settling internal quarrels between sub-rulers, and mediating between those sub-rulers and their people. The Alaafin of Oyo was also