WTH are you talking about? When the Dutch started settling the south of Africa in the 17th century there was no one there! The first conflicts arose with the Xhosa people who migrated in from the north-east.
Blacks don't have any prior rights to South Africa.
That is an ignorant statement. The Brits annexed the Dutch and most of South Africa and made it a colony of the Empire. Africans were not treated as equals under British rule and later South African rule. 20 percent tried to rule the remaining 80 percent. There are consequences for such an approach to governing.