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 Venezuela, Saint Lucia, Jamaica, Brazil, Grenada, and Trinidad and Tobago, and other countries. As an ethnic description, the word "Yoruba" (or more correctly, "Ya raba") was originally in reference to the Oyo Empire and is the usual Hausa name for Oyo people as noted by Hugh Clapperton and Richard Lander. It was therefore popularized by Hausa usage and ethnography written in Ajami during the 19th century by Sultan Muhammad Bello. The extension of the term to all speakers of dialects related to the language of the Oyo (in modern terminology North-West Yoruba) dates to the second half of the 19th