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 world noted for its art, and the Oyo Empire, the Benin Empire of the Edo people centred in Benin City, the Igbo Kingdom of Nri which produced advanced bronze art at Igbo-Ukwu, and the Akan who are noted for their intricate architecture. Central Africa saw the birth of several states, including the Kingdom of Kongo. In what is now modern Southern Africa, native Africans created various kingdoms such as the Kingdom of Mutapa. They flourished through trade with the Swahili people on the East African coast. They built large defensive stone structures without mortar such as Great Zimbabwe, capital of the