So with the recent South African controversy I've seen it repeated quite a few times on reddit, in highly upvoted comments, that the current black population of South Africa aren't native to the land, but that they arrived much later (even later than the Dutch and English did) and ethnically cleansed the original native population. Some go as far as to say that as there are no remaining "original natives" of South Africa, the white people are the real natives.
However, when I decided to do a quick research on Google, I couldn't find anything on the subject.
How much truth is there in that?
None. It is bullshit to legitimize White peoples claims to land.
That argument is often called the empty land myth, or the "equal invaders" theory. South Africa History Online provides an overview of the intellectual history of the myth here along with references for further reading.
A variant of this myth alleges that the violence that surrounded the building of the Zulu kingdom (the Mfecane), led to a sort of refugee wave that emptied out the eastern coast and highveld when Boers arrived.
/u/Khosikulu has provided some excellent answers about the empty land myth and the mfecane here, here and here which also add a lot more context and additional references.