Portuguese navigators discovered the uninhabited island in the late 15th century. It was annexed 100 years later and became a slavery hub and transhipment centre. In 1875, when slavery was abolished, contract labour was introduced. There were large numbers of rebellions over the years against Portuguese colonists. In 1975, after President Salazar’s fall in Portugal, the nationalist movement gained importance. The movement forced the Portuguese government to retreat and the country gained its independence.
Sao Tome and Principe continue to maintain relations with other Portuguese colonies and their neighbours, Gabon, Cameroon and Equatorial Guinea. The country was also used as a Soviet satellite until President Manuel Pinto da Costa declared that the country would not align. After mediating talks were successful, the civil war in Angola came to an end.
In March 1990, a new constitution was introduced and a crucial election followed in 1991. PCD won control of the national assembly and presidency. Democratic politics saw ups and downs when rebels took control in 2003 for several days. With the recent discovery of oil fields in Sao Tome’s territorial waters, the economic stakes of the country improved. The government benefited from commercial drilling and promises to take the country out of a debt-ridden situation. Efforts are being made to modernize the country's services.