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 al-Salih into his ranks. By doing this, he hoped to secure the support of Yoruba Muslims and volunteers from the Hausa-Fulani north in keeping Ilorin independent. Torn by internal struggle, Oyo could not defend itself against the Fulani. Oyo-Ile was razed by the Fulani Empire in 1835 and the Oyo Empire collapsed in 1836. To this day, the Illorin traditional ruler is an emir, whereas in the rest of Yoruba towns the rulers are called "oba" or "baale" (Baale or Baba Onile meaning "father of the land" or "lord of the land"). After the destruction of Oyo-Ile, the capital was