Several weeks ago we had a brief discussion of a somewhat
idiosyncratic list of "100 Great Africans." As I recall, at that
time there was some discussion of what made a person great, and even
who was great in the African context. There may have been some
reference here (or was it elsewhhere) to the Africans who made made
the European "explorers" successful.
At that time I thought of a reference to call to your attention, but
was unable to come up with more than very partial information. Now
[perhaps not too late! :-) ] I have found it!
Donald Simpson, *Dark Companions: The African Contribution
to the European Exploration of Africa* (New York: Barnes &
Noble, 1976).
I believe there is also a British edition, but I don't have those
details.