Answer:
   
   This group lives in a region in the north of S.A. known as Venda.
   Apparently early Jewish traders in S.A. found that certain Africans in
   Venda practised kashrut and other Jewish practises, and historical
   records of the Boer republics mention black Jews.
   
   There are supposedly 300,000 such Jews in S.A.; they claim to be
   descendants of a group of Yemenite Jews who migrated south and
   intermarried with the locals. Supposedly, there are similar groups all
   along the east coast of Africa. Of particular interest are 40000
   members of the black Lemba people. Like the Abayudaya, these people
   are keen to learn more about Jewish laws and practices. These claims
   of the Lemba are documented at
   [5]http://www.ubalt.edu/kulanu/africa.html.
   
   On the other hand, there is a book about this group (called the
   Lembe') called Voyage to the Invisible City. The author, Tudor Parfitt
   lives with them, studies them and sifts through the early records of
   the area, and concludes (over their objections of course) that their
   "jewish" traits come from Islam, not Judaism. They appear to him to be
   a mixture of locals, Hindus from India (they have lots of ancestor
   worship mixed in too) and Islam (they circumcise at 13 not in the
   first few weeks). He originally concluded that there is little
   likelihood that they have any real Jewish ancestry.
   
   Recently, Kohen Madol Haplotype testing has been performed among the
   Lemba; these tests have proven the Lemba to have the highest
   concentration of the gene marker than any known halakhic Jewish group.
   This is reported in an article titled "Decoding the Priesthood" by
   Peter Hirshberg and Jane Logan, in Jerusalem Report (May 10, 1999
   issue). According to this article, the Lemba have the same proportion
   of the gene as "Western" Jews and a remarkably high frequency among
   their Buba clan, a senior clan parallel to our Cohens.