s of the south kept the
district of Kentucky a No Man's Land, in convenient vacancy for
occupation by the white settlers, when they began the westward
movement.[156] [Map page 156.]

[Sidenote: Slavery as form of historical movement.]

This desolation is produced partly by killing, but chiefly by
enslavement of prisoners and the flight of the conquered. Both
constitute compulsory migrations of far-reaching effect in the fusion of
races and the blending of civilizations. The thousands of Greek slaves
who were brought to ancient Rome contributed to its refinement and
polish. All the nations of the known world, from Briton to Syrian and
Jew, were represented in the slave markets of the imperial capital, and
contributed their elements to the final composition of the Roman people.
When we read of ninety-seven thousand Hebrews whom Titus sold into
bondage after the fall of Jerusalem, of forty thousand Greeks sold by
Lucullus after one victory, and the auction _sub corona_ of whole tribes
in Gaul by Caesar, the scale of this forcible transfer becomes apparent,
and its power as an agent of race amalgamation. Senator Sam Houston of
Texas, speaking of the Comanche Indians, in the United States Senate,
December 31, 1854, said: "There are not less than two thousand prisoners
(whites) in the hands of the Comanches, four hundred in one band in my
own state.... 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States, superseded the native Indian stock of the Antilles by negroes,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