Not too long ago I'd read an intriguing paper by Roger Blench about ancient pastoralist Cushitic speaking peoples who culturally influenced the Khoikhoi groups of Southern Africa and noticed how this correlated with the genetic data on some of these populations they were known to have culturally influenced in that these groups demonstrated what looked to be Cushitic admixture.  
This lot Roger Blench touched upon are generally known as "The Savanna Pastoral Neolithic Culture", a culture at the earliest dating back to ~3200 BCE in the Kenyan lowlands, with a later presence in the Tanzanian highlands by ~1200 BCE and an even later presence in parts of Southern Africa as early as ~200 BCE.  
They were Cushitic (South Cushitic) speaking cattle pastoralists (whilst also possessing goats and sheep) and tended to bury their dead in cairns whilst their toolkit was characterized by stone bowls, pestles, grindstones and earthenware pots. Some even suggest that they practiced irrigation and cultivated grains such as millet though there's still some arguing to be done about that.  
They ultimately ended up spreading pastoralism across Southeastern and Southern Africa prior to the Bantu expansion.
But what this post is ultimately about is not explaining this culture to you (reading Blench's paper, their Wikipedia page and several other books or papers on them can do that for you just fine) but touching upon the genetic impact they seemingly left on the group's they culturally influenced in Southern Africa.
|Afar nomadic tent
|Nama nomadic tent
What you see above is one example of a cultural influence the peoples of the Savanna Pastoral Neolithic culture left in Southern Africa... They passed on what Roger Blench identifies as a signature form of tent making among Cushitic speaking peoples in Northeast Africa to Khoikhoi / Khoe-Kwadi speaking peoples like the Nama.
Bejas, Afars, Somalis, Rendilles and so on all practice or historically practiced this method of raising tents that Blench refers to as "mat-houses" or some refer to as "mat-tents".
|A painting of Khoikhoi pastoralists dismantling their tent
They also notably passed pastoralism onto some of these Hunter-Gatherer groups in Southern Africa prior to the arrival of Bantu-speakers after the Bantu expansion.
|Modern spread of the Bantu (a subset of Niger-Congo) languages in Africa
It's quite interesting in that this means that Cushites were in Southern Africa before Bantu speaking peoples made their way there and were the first peoples to spread the fruits of the Neolithic Revolution across the region until Bantu agriculturalists and pastoralists arrived & absorbed both them and various "Khoisan" groups.
Now, whilst I can go on and on about the cultural influences these peoples left on groups like the Nama; you can read about that in Blench's paper or from other sources. What I'm delving into here is what looks to be actual genetic evidence for this contact that seems quite undeniable in an archaeological sense.
Virtually all of these groups got their West Eurasian ancestry not from actual West Eurasians (though the Nama are more complicated and do have some European admixture) but from West Eurasian admixed East African pastoralists similar for example to your average Somali.
I made a point of contacting the geneticist in charge of the study responsible for the above table via email:
I asked him quite directly if this West Euraisan ancestry in his opinion was owed to West Eurasians or to Cushitic speakers/ peoples genetically similar to ethnic Somalis and even shared Roger Blench's old paper with him to show him what I was talking about.
I did so because many of the peoples his study had sampled (Khoe-Kwadi speaking groups like the Nama) were coincidentally the very peoples Roger Blench and others have touched upon and pegged for having a Cushitic-Afro-Asiatic cultural influence about them.
He seemed to agree with this as you can see above and believes they got their West Eurasian ancestry from East African pastoralists who themselves were West Eurasian admixed (basically like the Northeast African Cushitic speakers his study also tested) and to me; this + the known and solid Cushitic cultural influence in these groups definitely confirms this to be Cushitic admixture.
The study he acted as a main author for ultimately demonstrates this:
The Nama were excluded from this table because their European admixture complicates things but above you can see these groups basically modeled as "Khoisan + Cushitic + Bantu". With the Eastern African ancestry carrying West Eurasian admixture with it being their Cushitic admixture as in this table it's ultimately similar to the ancestry in the study's West Eurasian admixed Eastern African populations (Somalis, Oromos et al.):
In the end; it's quite interesting to know that South Cushites didn't just leave a genetic and cultural impact on Southeast Africa as I touched upon in the past but also made it as far as Southern Africa where it seems that they both culturally and genetically influenced various peoples across the region.
1. Was there an interchange between Cushitic pastoralists and Khoisan speakers in the prehistory of Southern Africa and how can this be detected? , Roger Blench
3. From Hunters to Farmers: The Causes and Consequences of Food Production in Africa, by John Desmond Clark, Steven A. Brandt