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 After this, Oba Orompoto led attacks to obliterate the Nupe to ensure Oyo was never threatened by them again. During the reign of Oba, Ajiboyede, he held the first Bere festival, an event to celebrate peace in the kingdom. Celebrated regularly, it would retain much significance among the Yoruba long after the fall of Oyo. Under his successor, Abipa, the Yoruba repopulated Oyo-Ile and rebuilt the original capital. Despite a failed attempt to conquer the Benin Empire sometime between 1578 and 1608, Oyo continued to expand. The Yoruba allowed autonomy to the southeast of metropolitan Oyo, where the non-Yoruba areas