For a purely fictional accounts of precolonial Africa, one with nary a
factual nail on which to hang a hat,
take a look at H. Rider Haggard's *She* -- a Conan Doyle-like, "lost
worlds" account of the original
She-Who-Must-Be-Obeyed.  Features two African "tribes": the dull and savage
ones along the
(eastern) coast, and the clever but treacherous mountain folk.  And one
really conflicted woman.

Haggard cranked out a number of similar African fantasies.

Brian Siegel