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
Yoruba people There are three major dialect areas: Northwest, Central, and Southeast. As the North-West Yoruba dialects show more linguistic innovation, combined with the fact that Southeast and Central Yoruba areas generally have older settlements, suggests a later date of immigration for Northwest Yoruba. The area where North-West Yoruba (NWY) is spoken corresponds to the historical Oyo Empire. South-East Yoruba (SEY) was probably associated with the expansion of the Benin Empire after c. 1450. Central Yoruba forms a transitional area in that the lexicon has much in common with NWY, whereas it shares many ethnographical features with SEY. Literary Yoruba, the standard