Oyo Empire culture in Oyo where victory was obligatory and defeat carried the duty of committing suicide. This do-or-die policy no doubt contributed to the military aggressiveness of Oyo's generals. The Oyo Empire was the only Yoruba state to adopt cavalry; it did so because most of its territory was in the northern savannah. The origin of the cavalry is disputed; however, the Nupe, Borgu and Hausa in neighboring territories also used cavalry and may have had the same historical source. Oyo was able to purchase horses from the north and maintain them in metropolitan Oyo because of partial freedom from the
Oyo Empire in the present Oyo died in 1905. See List of rulers of the Yoruba state of Oyo. During the colonial period, the Yorubas were one of the most urbanized (living in city-like areas) groups in Africa. About 22% of the population lived in large areas with population exceeding 100,000 and over 50% lived in cities made up of 25,000 or more people. The index of urbanization in 1950 was close to that of the United States, excluding Ilorin. The Yoruba continue to be the most urbanized African ethnic group today. Old Oyo linked cities such as Ibadan, Osogbo, and Ogbomoso,