History is always being revised, simply because history is a tool with which to make sense of your present and since your present is always changing, history also changes.
If history was only facts, this would not be so. But the facts are only the dots and dots as we know can be linked in many ways depending on the picture you want to make.
I am 42 and I have experienced history under Apartheid and history post-Apartheid. I was told as a child that South Africa was empty when white people arrived in 1652. A small footnote was usually added here - the Dutch found Hottentots and San (Bushmen), but since all of them are now extinct, they are not important. As white people moved from the south to the north, black people moved from Central Africa to Southern-Africa and they met at the Kei River. So black people did not have right to the country, since white people were there first. This and many other historical "facts" were used to give a historical basis for Apartheid.
I read many different accounts of history in the dying days of Apartheid. Creating alternative histories was one of the ways in which Apartheid was fought. Never underestimate the power of stories. Yes, a big part of the interior of South Africa was empty when the first Boers arrived, but that was because the Zulu warriors drove many black groups into what is now Zimbabwe. Of course many black groups stayed. The Hottentots were not all killed by European diseases or because the whites stole their land and cattle. Many of them lived on to become Griquas, whose land (full of diamonds) was stolen first by Boers and then Britain, but oh, that is another story.
Once, white families eliminated all traces of black ancestry from their family trees. Now those black dots are desirable and linked into a narrative that integration between black and white had taken place in the past.
Do I appear cynical?
Yes, I believe in truth. Truth is full of buts and maybes and asides and complications. If a history points to only one future, I suspect it of simplification. If history is unclear, I suspect one should choose your ethical ideal and look for facts to support it. And when it comes to ethics, I do believe in right and wrong and Apartheid was wrong.