"True" Black Africans appear as a recent adaptive radiation in the above dendrograms, apparently branching off from an ancestral Pygmy population — a line of ancestry also indicated by osteological data (Coon 1962:651-656; Watson et al. 1996). This radiation seems to have occurred somewhere in West Africa. Before the Bantu expansion about 3,000 years ago, true Black Africans were absent from the continent's central, eastern, and southern regions (Cavalli-Sforza 1986:361-362; Oliver 1966). They were also absent from the middle Nile until about 4,000 years ago, at which time they begin to appear in paintings from Pharaonic Egypt and in skeletal remains from Nubia (Junker 1921).
For more detailed information about the racial differences between pre-historic and modern sub-Saharan Africans, see the work of anthropologist W.W. Howells.