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 century. It is due to the influence of Bishop Samuel Ajayi Crowther, the first Anglican bishop in Nigeria. Crowther was himself an Oyo Yoruba and compiled the first Yoruba dictionary as well as introducing a standard for Yoruba orthography. The alternative name "Akú", apparently an exonym derived from the first words of Yoruba greetings (such as "Ẹ kú àárọ?" "good morning", "Ẹ kú alẹ?" "good evening") has survived in certain parts of their diaspora as a self-descriptive, especially in Sierra Leone. The Yoruba culture was originally an oral tradition, and the majority of Yoruba people are native speakers of the