Since its formation in the 1950s, the MPLA's main social base has been among the Ambundu people and the multiracial intelligentsia of cities such as Luanda, Benguela and Huambo. During its anti-colonial struggle of 1962–1974, the MPLA was supported by several African countries, as well as by the Soviet Union. In the decolonization conflict of 1974-5, Cuba became the MPLA's strongest ally, sending significant contingents of combat and support personnel to Angola. This support, as well as that of several other countries of the Eastern Bloc, e.g. Romania and East Germany, was maintained during the Civil War.
The FNLA formed parallel to the MPLA, and was initially devoted to defending the interests of the Bakongo people and supporting the restoration of the historical Kongo Empire. However, it rapidly developed into a nationalist movement, supported in its struggle against Portugal by the government of Mobutu Sese Seko in Zaire. During the early 1960s, the FNLA was also supported by the People's Republic of China, but when UNITA was founded in the mid-1960s, China switched its support to this new movement, because the FNLA had shown little real activity. The United States refused to give the FNLA support during the movement's war against Portugal, which was a NATO ally of the U.S.; however, the FNLA did receive U.S. aid during the decolonization conflict and later during the Civil War.
UNITA's main social basis were the Ovimbundu of central Angola, who constituted about one third of the country's population, but the organisation also had roots among several less numerous peoples of eastern Angola. UNITA was founded in 1966 by Jonas Savimbi, who until then had been a prominent leader of the FNLA. During the anti-colonial war, UNITA received some support from the People's Republic of China. During the subsequent decolonization conflict, the United States decided to support UNITA, and considerably augmented their aid to UNITA during the Civil War. However, in the latter period, UNITA's main ally was the State of South Africa