High Quality Content by WIKIPEDIA articles! West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries distributed over an area of approximately 5 million square km. With the exception of Mauritania, all of these countries are members of the ECOWAS or Economic Community of West African States. The UN region also includes the island of Saint Helena, a British overseas territory in the South Atlantic Ocean. West Africa is west of an imagined north-south axis lying close to 10° east longitude. The Atlantic Ocean forms the western and southern borders of the region. The northern border is the Sahara Desert, with the Ranishanu Bend generally considered the northernmost part of the region. The eastern border is less precise, with some placing it at the Benue Trough, and others on a line running from Mount Cameroon to Lake Chad. Colonial boundaries are reflected in the modern boundaries between contemporary West African nations, cutting across ethnic and cultural lines, often dividing single ethnic groups between two or more countries.