Oyo Empire could act as a buffer between Oyo and Imperial Benin. By the end of the 16th century, the Ewe and Aja states of modern Benin were paying tribute to Oyo. The reinvigorated Oyo Empire began raiding southward as early as 1682. By the end of its military expansion, Oyo's borders would reach to the coast some southwest of its capital. It met little serious opposition until the early 18th century. In 1728, the Oyo Empire invaded the Kingdom of Dahomey in a major campaign of its cavalry. Dahomey warriors, on the other hand, had no cavalry but many firearms. Their
Yoruba people the monarchy was open to the election of any free-born male citizen. In Ilesa, Ondo, Akure and other Yoruba communities, there were several, but comparatively rare, traditions of female "Ọbas". The kings were traditionally almost always polygamous and often married royal family members from other domains, thereby creating useful alliances with other rulers. Ibadan, a city-state and proto-empire founded in the 18th century by a polyglot group of refugees, soldiers, and itinerant traders from Ọyọ and the other Yoruba sub-groups largely dispensed with the concept of monarchism, preferring to elect both military and civil councils from a pool of eminent