Oyo Empire metropolitan Oyo. This may have been fine in the 15th century when Oyo controlled only its heartland. But to make and maintain farther conquest, the structure underwent several changes. Oyo maintained a semi-standing army of specialist cavalry soldiers called the "Eso", the "Esho" or, formally, the Eso of Ikoyi. These were 70 junior war chiefs who were nominated by the Oyo Mesi and confirmed by the Alaafin of Oyo. The Eso were appointed for their military skill without regard to heritage and were led by the Are-Ona-Kakanfo. After Oyo's return from exile, the post of Are-Ona-Kakanfo was established as the
History of the Yoruba people the settlement at Ile-Ife can be dated to the 4th century BC, with urban structures appearing in the 12th century (the urban phase of Ile-Ife before the rise of Oyo, ca. 1100-1600, is sometimes described as a "golden age" of Ile-Ife). Ife was surpassed by the Oyo Empire as the dominant Yoruba military and political power between 1600 and 1800 AD. The nearby kingdom of Benin was also a powerful force between 1300 and 1850. The Oyo was developed in the 17th century and become one of the largest Yoruba kingdoms, while Ile-Ife remained as a religious significance at the