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 century. It is due to the influence of Bishop Samuel Ajayi Crowther, the first Anglican bishop in Nigeria. Crowther was himself an Oyo Yoruba and compiled the first Yoruba dictionary as well as introducing a standard for Yoruba orthography. The alternative name "Akú", apparently an exonym derived from the first words of Yoruba greetings (such as "Ẹ kú àárọ?" "good morning", "Ẹ kú alẹ?" "good evening") has survived in certain parts of their diaspora as a self-descriptive, especially in Sierra Leone. The Yoruba culture was originally an oral tradition, and the majority of Yoruba people are native speakers of the