Angola, officially the Republic of Angola (Portuguese: República de Angola,), is a country in south-central Africa bordered by Namibia on the south, Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean. The exclave province of Cabinda has a border with the Republic of the Congo and the Democratic Republic of the Congo. Angola was a Portuguese overseas territory from the 16th century to 1975. The country is the second-largest petroleum and diamond producer in sub-Saharan Africa; however, its life expectancy and infant mortality rates are both among the worst ranked in the world. According to the International Monetary Fund, more than $4 billion in oil receipts have disappeared from Angola's treasury in the 2000s. In August 2006, a peace treaty was signed with a faction of the FLEC, a separatist guerrilla group from the Cabinda exclave in the North, which is still active.About 65% of Angola's oil comes from that region.