Note 159 — Chapter IV · —The Movements Of Peoples In Their Geographical Significance

In Africa slavery has been intimately associated with agriculture as a source of wealth, and therefore has lent motive to intertribal wars. Captives were enslaved and then gradually absorbed into the tribe of their masters. Thus war and slavery contributed greatly to that widespread blending of races which characterizes negro Africa. Slaves became a medium of exchange and an article of commerce with other continents. The negro slave trade had its chief importance in the eyes of ethnologists and historians because, in distributing the black races in white continents, it has given a "negro question" to the United States, superseded the native Indian stock of the Antilles by negroes, and left a broad negro strain in the blood of Colombia, Venezuela, and Brazil. This particular historical movement, which during the two centuries of its greatest activity involved larger numbers than the Tartar invasion of Russia or the Turkish invasion of Europe, for a long period gave to black Africa the only historical importance which it possessed for the rest of the world.159