Most Rh- Africans are not truly Rh-

The presence of an RHD pseudogene containing a 37 base pair duplication and a nonsense mutation in Africans with the Rh D-negative blood group phenotype

From the study above:

All techniques for predicting D phenotype from DNA or mRNA are based on the dogma that, with only very rare exceptions, the D-negative phenotype results from the absence of all or most of the RHDgene. Most tests, however, have been performed on people of European origin, and the molecular basis of D polymorphism has not been adequately investigated in other races, particularly in people of African origin. We have tested for the presence of the RHD gene in Africans and African Americans and found that the majority of D-negative Africans and about a quarter of D-negative African Americans have an inactive RHD gene with a 37 base pair (bp) insert and a nonsense mutation; the remainder have either the RHD-CE-D gene or a complete deletion of the RHD gene.

Is Rh- blood Caucasoid?

So who are the African minority with true Rh- blood?

Tribes with truly Rh- blood, tend to get it from North African, European and West Asian ancestors:

Most Rh- Africans are not truly Rh- II