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
Nigeria of Igbo culture. Nri and Aguleri, where the Igbo creation myth originates, are in the territory of the Umeuri clan. Members of the clan trace their lineages back to the patriarchal king-figure Eri. In West Africa, the oldest bronzes made using the lost-wax process were from Igbo-Ukwu, a city under Nri influence. The Yoruba kingdoms of Ife and Oyo in southwestern Nigeria became prominent in the 12th and 14th centuries, respectively. The oldest signs of human settlement at Ife's current site date back to the 9th century, and its material culture includes terracotta and bronze figures. Oyo, at its territorial