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
Shaki, Oyo Shaki, Oyo Shaki (also Saki) is a town situated in the northern part of Oyo State in western Nigeria. The terrain is hilly. The town lies near the source of the Ofiki River, the chief tributary of the Ogun River, about 40 miles (60 km) from the Benin border. It is referred to as the food basket of Oyo State because of its agricultural activities. It is the headquarters of Saki West local government authority. Originally part of the Oyo Empire, Shaki became a Yoruba refugee settlement after the destruction in 1835 of Old Oyo (Katunga), 70 miles (113 km)