query: When did Angola become an independent country?
passage: History of Angola
Angola is a country in southwestern Africa. The country's name derives from the Kimbundu word for king.. It was first settled by San hunter-gatherer societies before the northern domains came under the rule of Bantu states such as Kongo and Ndongo. From the 15th century, Portuguese colonists began trading, and a settlement was established at Luanda during the 16th century. Portugal annexed territories in the region which were ruled as a colony from 1655, and Angola was incorporated as an overseas province of Portugal in 1951. After the Angolan War of Independence, which ended with an army mutiny and leftist coup in Lisbon, Angola's independence was achieved on November 11, 1975 through the Alvor Agreement. After independence, Angola later entered a period of civil war that lasted up until 2002.
passage: Colonial history of Angola
Whilst the economic development of the country was not entirely neglected and many useful food products were introduced, the prosperity of the province was very largely dependent on the slave trade with the Portuguese colony of Brazil, which was not legally abolished until 1830 after Brazil's independence from Portugal (1822) and in fact continued for many years subsequently. Many scholars agree that by the 19th century, Angola was the largest source of slaves not only for Brazil, but for the Americas, including the United States. By the end of the 19th century, a massive forced labour system had replaced slavery and would continue until outlawed in 1961. Portuguese colonial rule in the twentieth century was characterized by rigid dictatorship and exploitation of African labor.