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,
Yoruba people the monarchy was open to the election of any free-born male citizen. In Ilesa, Ondo, Akure and other Yoruba communities, there were several, but comparatively rare, traditions of female "Ọbas". The kings were traditionally almost always polygamous and often married royal family members from other domains, thereby creating useful alliances with other rulers. Ibadan, a city-state and proto-empire founded in the 18th century by a polyglot group of refugees, soldiers, and itinerant traders from Ọyọ and the other Yoruba sub-groups largely dispensed with the concept of monarchism, preferring to elect both military and civil councils from a pool of eminent