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 or Oyo-oro). The two most important structures in Oyo-Ile were the 'Afin,' or palace of the Oba, and his market. The palace was at the center of the city close to the Oba's market called 'Oja-Oba'. Around the capital was a tall earthen wall for defense with 17 gates. The importance of the two large structures (the palace and the Oja Oba) signified the importance of the king in Oyo. Oyo had grown into a formidable inland power by the end of the 14th century. For over a century, the Yoruba state had expanded at the expense of its neighbors.