The former policy of the south african government that was designed to maintain the separation of blacks and other non-whites from the dominant whites was known as

Apartheid

Explanation:

Apartheid was a institutionalised segregation system lasting from 1948, to 1990 in South Africa and Namibia,

White race dominated the other races  by legal means (Population Registrarion Act). Whites had acces to social events of importance, acces to priviledges , public facilities and better treatment by goverment officials.

Blacks among other miniorities were continiously repressed.

A minority of whites ruled the country, prior to 1940, and established the unjust system which would be fought by Nelson Mandela later on.

Unfortunately the economic legacy and the social impact of the Apartheid remain until present time.

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there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.