Northwestern Nigeria experiences a mixing of cultural traditions as various ethnic groups enter the region following the disintegration of Hausa and Yoruba states and the organization of the Sokoto caliphate in that region. To the southwest, Abeokuta becomes a celebrated center of Yoruba wood carving as noted sculptors establish workshops there, while its neighbors to the west, the Anago and Ketu Yoruba, develop the gelede masquerade. Elsewhere on the Guinea coast, ex-slaves from Europe and the Americas return to Africa and settle at Sierra Leone, Liberia, and other points along the coastline. Their ranks are augmented by liberated slaves confiscated by the British Navy as it enforces its ban on the international slave trade. Well-educated and highly skilled, these populations comprise a successful mercantile class that constitutes an economic and cultural bridge between European and African peoples. The Asante and Dahomey states continue to expand their economic and territorial interests, but by the latter half of the century their ascendance is checked by the emerging European colonial presence.