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 al-Salih into his ranks. By doing this, he hoped to secure the support of Yoruba Muslims and volunteers from the Hausa-Fulani north in keeping Ilorin independent. Torn by internal struggle, Oyo could not defend itself against the Fulani. Oyo-Ile was razed by the Fulani Empire in 1835 and the Oyo Empire collapsed in 1836. To this day, the Illorin traditional ruler is an emir, whereas in the rest of Yoruba towns the rulers are called "oba" or "baale" (Baale or Baba Onile meaning "father of the land" or "lord of the land"). After the destruction of Oyo-Ile, the capital was