Oyo Empire gunshots scared the Oyo cavalry horses and prevented their charging. Dahomey's army also built fortifications such as trenches, which forced the Oyo army to fight as infantry. The battle lasted four days, but the Yoruba were eventually victorious after reinforcements arrived. Dahomey was forced to pay tribute to Oyo. The Yoruba invaded Dahomey seven times before finally subjugating the small kingdom in 1748. With its cavalry, Oyo campaigned successfully in conquest and suppression over great distances. The Oyo army was able to attack defensive fortifications, but it was harder to supply an army, and they withdrew when supplies ran out.
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