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
Oyo Empire became the southern emporium of the Trans-Saharan trade. Exchanges were made in salt, leather, horses, kola nuts, ivory, cloth and slaves. The Yoruba of metropolitan Oyo were also highly skilled in craft making and iron work. Aside from taxes on trade products coming in and out of the empire, Oyo also became wealthy off the taxes imposed on its tributaries. Taxes on the kingdom of Dahomey alone brought in an amount estimated at 638 thousand dollars a year. By 1680, the Oyo Empire spanned over 150,000 square kilometers. It reached the height of its power in the 18th century. And