Dejima (Japanese: 出島, "exit island"), in old Western documents latinized as 'Decima', 'Desjima', 'Dezima', 'Disma', or 'Disima', was a small fan-shaped artificial island built in the bay of Nagasaki in 1634 by local merchants. This island, which was formed by digging a canal through a small peninsula, remained as the single place of direct trade and exchange between Japan and the outside world during the Edo period. Dejima was built to constrain foreign traders as part of sakoku, the self-imposed isolationist policy.