Portuguese Angola Portuguese protectorate by the 1885 Treaty of Simulambuco. Sometime during the 1920s, it became incorporated into the larger colony (later the overseas province) of Portuguese Angola. The two colonies had initially been contiguous, but later became geographically separated by a narrow corridor of land, which Portugal ceded to Belgium allowing Belgian Congo access to the Atlantic Ocean. Following the decolonisation of Portuguese Angola with the 1975 Alvor Agreement, the short-lived Republic of Cabinda unilaterally declared its independence. However, Cabinda was soon overpowered and re-annexed by the newly proclaimed People's Republic of Angola and never achieved international recognition. Portuguese explorers and
1950s in Angola of Northern Angola, which advocated the independence of the traditional Kingdom of Kongo, in 1954. Portuguese police arrested Agostinho Neto of the MPLA and future President of Angola (1975–1979), in 1952 and again in 1955 for his involvement in the Portuguese Communist Party. He returned to Angola in 1959 and police arrested him again in 1960. Portuguese authorities arrested over 100 MPLA members in 1959. The Portuguese discovered petroleum in Angola in 1955. Production began in the Cuanza basin in the 1950s, in the Congo basin in the 1960s, and in the exclave of Cabinda in 1968. The Belgian company