The Atlantic slave trade peaked in the late 18th century, when the largest number of slaves were captured on raiding expeditions into the interior of West Africa. The increase of demand for slaves due to the expansion of European colonial powers to the New World made the slave trade much more lucrative to the West African powers, leading to the establishment of a number of actual West African empires thriving on slave trade. These included Oyo empire (Yoruba), Kong Empire, Kingdom of Benin, Imamate of Futa Jallon, Imamate of Futa Toro, Kingdom of Koya, Kingdom of Khasso, Kingdom of Kaabu, Fante Confederacy, Ashanti Confederacy, and the kingdom of Dahomey. The gradual abolition of slavery in European colonial empires during the 19th century again led to the decline and collapse of these African empires.