Bingo. Same thing has been happening in the US. We went for a long time without having to give border security much thought. Now shitbags come from all over for the gibs.

Wasn't there some story about the water supply running out?

There were no Bantus or Zulu in South Africa when the whites arrived. There was a very very sparse population of Khoi-san hunter-gatherers, like the tribe in "The Gods Most be Crazy". The Zulu, who were the farthest edge of the Bantu expansion, didn't meet whites until whites went far north, while they had themselves been traveling south for a long time. They had been genociding and replacing Khoi-san type tribes for centuries prior, and only got stopped by the Boers.