Earlier quoted context omitted.
Tribalism is often encouraged by invaders and colonizers. Divide and Conquer is a classic tactic. See Tutsi Vs Hutu for one notable example in Africa. And this was a known strategy in apartheid South Africa.
Is this really blamed on Apartheid? Whenever I have talked with South African Blacks about the various tribal affiliations of the country, they claim that each community did not much like each other (and everyone hated the Zulus) since long before white people arrived. Indeed, it was white oppression that gave an impetus to pan-Africanism where, for a time in the ANC, people might have united across tribal affiliatio…
You could make the argument that it was always going to be a problem and the colonizers didn't materially affect the course of history.
What you can't do is argue they didn't intentionally take advantage of this split for their own purposes. Because they did and it's documented history.
edit to add:
Here's a pro-apartheid Quora answer that suggests the separation of the different tribes was necessary to stop communists from stealing South Africa's mineral wealth.
> Apartheid gave these tribes their land back. Apartheid gave each tribe his independence from White Rule. Yes you lived ‘apart’ from the whites. But you lived apart in your own country. You could choose your own leaders and government and destiny.
> Communism was one of the driving forces to push the Black Independence program. The communists were using the blacks to try out vote the whites so that they could get control of of SAs mineral resources. By dividing SA into several smaller countries you effectively defeated the Communist plan.