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 Venezuela, Saint Lucia, Jamaica, Brazil, Grenada, and Trinidad and Tobago, and other countries. As an ethnic description, the word "Yoruba" (or more correctly, "Ya raba") was originally in reference to the Oyo Empire and is the usual Hausa name for Oyo people as noted by Hugh Clapperton and Richard Lander. It was therefore popularized by Hausa usage and ethnography written in Ajami during the 19th century by Sultan Muhammad Bello. The extension of the term to all speakers of dialects related to the language of the Oyo (in modern terminology North-West Yoruba) dates to the second half of the 19th