HISTORY. Guinea-Bissau formerly, Portuguese Guinea, on the coast of Guinea, was discovered in 1446 by Nuno Tristăo. It became a separate colony in 1879. It is bounded by the limits fixed by the convention of 12 May 1886 with France. In 1951 Guinea-Bissau became an overseas province of Portugal. On 10 Sept. 1974 Portugal formally recognized the independence of Guinea-Bissau.