The land now known as Guinea-Bissau was once the kingdom of Gabú, which was part of the larger Mali empire. After 1546 Gabú became more autonomous, and at least portions of the kingdom existed until 1867. The first European to encounter Guinea-Bissau was the Portuguese explorer Nuño Tristão in 1446; colonists in the Cape Verde islands obtained trading rights in the territory, and it became a center of the Portuguese slave trade. In 1879, the connection with the islands was broken.
The African Party for the Independence of Guinea-Bissau and Cape Verde (another Portuguese colony) was founded in 1956, and guerrilla warfare by nationalists grew increasingly effective. By 1974 the rebels controlled most of the countryside, where they formed a government that was soon recognized by scores of countries. The military coup in Portugal in April 1974 brightened the prospects for freedom, and in August the Lisbon government signed an agreement granting independence to the province. The new republic took the name Guinea-Bissau.