The country of Niger in West Africa is named after the great Niger River, the third-longest river in Africa (exceeded only by the Nile and the Congo). When Islam reached West Africa around 660, the peoples in the region of modern Niger lived in well-organized states that existed until the arrival of the French in the 19th century. In 1922 the region was integrated into the French colonial empire, and in 1960 gained independence as Republic of Niger. Niger uses the West African CFA franc, the currency of the West African Economic and Monetary Union (not to be confused with the Central African CFA franc, the single currency of the Central African states). This franc was introduced to the French colonies of West Africa in 1945, and since then has remained the single currency of most countries even after they became independent. This coin is not a circulation coin, however, but a non-circulating coin that belongs to a series of proof coins issued in the 1960s.