Evidence of a pastoralist migration through Tanzania to southern Africa

[Grant]

That is not a Cushitic trait. They get those behinds from the indigenous Khoisan genes. The San have it as well and more frequently than the Nama and they (San) are 0% Horner.

Exactly right. But they once covered all of Africa. Where did they go?

These maps are from the first link: http://www.pnas.org/content/105/31/10693.full

"A" is Bushmen in general. "B" is the group that became the Khoikhoi. Note that they did exist in the Horn. Now compare these maps to the "Back to Africa " map above. Given that we know the Khoikhoi sheep came through the Horn, the conclusion seems inescapable: they got pushed south by later immigrants, and were then decimated by the Bantu expansion and the colonial invasions.