They take no prisoners but women and boys."[157] It was customary among the Indians to use captured women as concubines and to adopt into the tribe such boys as survived the cruel treatment to which they were subjected.

Since the Comanches in 1847 were variously estimated to number from nine to twelve thousand,[158] so large a proportion of captives would modify the native stock.
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because, in distributing the black races in white continents, it has given a "negro question" to the United States, superseded the native Indian stock of the Antilles by negroes, and left a broad negro strain in the blood of Colombia, Venezuela, and Brazil.