Well, Sumer 6000 years old! I think we have gone back much further with that bunch, as having come out of the second garden between the rivers, which makes it at least 30 000 or so.
But the African builders may have been the orange race who loved to build in stone, that were later wiped out by the green man. Both carried giant strains so hoisting big rocks was probably not too much work :-)
Both races were absorbed by the later arriving indigo races. The orange ceased to exist about 100 000 yrs ago, so perhaps this is what this is all about? Fun!