Early civilisations, including Ethiopia, have been found in sub-Saharan Africa but dating back to early Christian times. I suspect little money and effort has been expended to find more within homo sapiens original home, certainly compared to the money spent on the search for ancient human fossils.
Simple assumptions, prejudice or the need to redefine civilisation? While the previous term is employed for settlements or cities, these are further defined as ones of stone or brick. Usually, they exhibited the same structural or design qualities with large central buildings and defined areas of settlement based on class.
In Central Asia at the time of the early great Sumerian cities like Uruk, a huge Kurgan complex of tents existed. Archaeologists and historians do not of course refer to it as a civilisation, at least in the same way they reference Sumeria.
If some attempt is made, will we find huge settlements of mud huts covering wide areas throughout the region? Will we also discover writing?