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 Africa. The historical Yoruba develop "in situ", out of earlier Mesolithic Volta-Niger populations, by the 1st millennium BCE. Oral history recorded under the Oyo Empire derives the Yoruba as an ethnic group from the population of the older kingdom of Ile-Ife. The Yoruba were the dominant cultural force in southern Nigeria as far back as the 11th century. The Yoruba are among the most urbanized people in Africa. For centuries before the arrival of the British colonial administration most Yoruba already lived in well structured urban centres organized around powerful city-states ("Ìlú") centred around the residence of the "Oba". In