In 1970, when the last official census was completed the population was 5.8 million. By 1975 it was estimated at 6.5 million.
Angola was bordered by Namibia to the south, Zambia to the east, Zaire to the north-east, and the South Atlantic to the west. The exclave of Cabinda also bordered the Congo to the north. Angola's capital, Luanda, lies on the Atlantic coast in the northwest of the country.
Crudely, the country can be divided into a coastal plain 60-100 km wide, a hilly and mountainous belt and a high plateau.
The climate is Angola's average temperature on the coast is 60 °F (16 °C) in the winter and 70 °F (21 °C) in the summer. It has two seasons; dry season (May to October) and hot rainy season (November to April). The vegetation is largely savannah with belts of tropical rain forest near major waterways.
The factions that fought the colonial war against the Portuguese, and each other, had their bases in different geographical regions. The National Front for the Liberation of Angola (FNLA) were strongest in the north and had troops in neighbouring Zaire, as it was in 1975. The Marxist MPLA, or People's Movement for the Liberation of Angola's, core support came from the the Mbundu ethnic group as well the educated intelligentsia in Luanda, and other urban centres, as well as Angolan activists in Portugal. The party had formal links with Soviet and East European Communist parties. UNITA, the National Union for the Total Independence of Angola, was founded in 1966. UNITA was led by Jonas Savimbi after he broke with the FNLA. UNITA's leadership was drawn largely from the Ovimbundu in the Central Southern region.