hunters with firearms had cleared
many areas and exterminated several species, including the quaggas, by the
end of the nineteenth
century. Much of the region could also support
domesticated animals, but tsetse flies and other bearers of diseases of cattle,
sheep, and goats have made pastoralism extremely hazardous in the trop-
icallands of the northeast. East and north of the twenty-inch rainfall zone,
arable agriculture is possible. Throughout Southern Africa, however, agri-
4