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
Ojigi (Oyo) Oyo. Ojigi (Oyo) Ojigi (also Ojiji) was Alaafin of the Yoruba Oyo Empire in what is now Nigeria from 1724-1735. Alaafin Ojigi's rule began Oyo's "great age of conquest". His reign is also considered the peak of imperial success, and Ojigi enjoyed the strong support of several important chiefs. Ojigi launched four military incursions against the Kingdom of Dahomey after the receiving requests for assistance from other kingdoms who were threatened by Agaja, the Dahomean king. In 1730 the Dahomeans agreed to begin paying an annual tribute of forty men, women, guns, and four hundred loads of cowries and corals