her than the more ephemeral advantage of trade, as were
those of the Dutch and Portuguese in the Tropics. It seems also
essential to these centers of dispersion, that, to be effective, they
must command the wide choice of outlet and destination afforded by the
mighty common of the sea. Only the Inca Empire in South America gives
us an example of the extensive political expansion of a small mountain
state.

[Sidenote: Tests of origin.]

The question arises whether any single rule can as yet be formulated for
identifying the original seats of existing peoples. By some ethnologists
and historians such homes have been sought where the people are
distributed in the largest area, as the Athapascan and Algonquin Indians
are assigned to a northern source, because their territories attained
their greatest continuous extent in Canada, but were intermittent or
attenuated farther south. The fact that colonial peoples often multiply
inordinately in new lands, and there occupy a territory vastly greater
than that of the mother country, points to the danger in such a
generalization. Of the ten millions of Jews in the world, only a handful
remain in the ancient center of dispersion in Palestine, while about
eight millions are found in Poland and the contiguous territories of
western Russia, Roumania, Austria-Hungary and eastern Germany. Moreover,
history and the German element in the "Yiddish" speech of the Russian
Jews point to a secondary center of dispersion in the Rhine cities and
Franconia, whither the Jews were drawn by the trade route up the Rhone
Valley in the third century.[238]

A more scientific procedure is to look for the early home of a race in
the locality around which its people or family of peoples centers in
modern times. Therefore we place the cradle of the negro race in Africa,
rather than Melanesia. Density often supplies a test, because colonial
lands are generally more sparsely inhabited than the mother country. But
even this conclusion fails always to apply, as in the case of Samos,
which has a population vastly more dense than any section of the Grecian
mainland. The largest compact area including at once the greatest
density of population and the greatest purity of race would more nearly
indicate the center of dispersion; because purity of race is
incompatible with long migrations, as we have seen, though in the native
seat it may be affected by intrusive elements. When this purity of race
is combined with