Sierra Leone is on the Atlantic coast of West Africa, with coastal swamps rising to interior plateaus and mountains. Named "lion mountain" by a 15th-century Portuguese explorer, Sierra Leone was a British colony from the early 19th century until 1961. In the 1990s democratically elected leaders were overthrown but subsequently regained power, and major hostilities have demoralized the population and destabilized the economy. In 2002 Sierra Leone emerged from a decade of civil war, with the help of some 17,000 UN peacekeepers.