was young, and in the densely populated countries of our
era. As the earth grew old and humanity multiplied, peoples themselves
became the greatest barriers to any massive migrations, till in certain
countries of Europe and Asia the historical movement has been reduced to
a continual pressure, resulting in compression of population here,
repression there. Hence, though political boundaries may shift, ethnic
boundaries scarcely budge. The greatest wars of modern Europe have
hardly left a trace upon the distribution of its peoples. Only in the
Balkan Peninsula, as the frontiers of the Turkish Empire have been
forced back from the Danube, the alien Turks have withdrawn to the
shrinking territory of the Sultan and especially to Asia Minor.

Where a population too great to be dislodged occupies the land, conquest
results in the eventual absorption of the victors and their civilization
by the native folk, as happened to the Lombards in Italy, the Vandals in
Africa, and the Normans in England. Where the invaders are markedly
superior in culture, though numerically weak, conquest results in the
gradual permeation of the conquered with the religion, economic methods,
language, and customs of the newcomers. The latter process, too, is
always attended by some intermixture of blood, where no race repulsion
exists, but this is small in comparison to the diffusion of
civilization. This was the method by which Greek traders and colonists
Hellenized the countries about the eastern Mediterranean and spread
their culture far back from the shores which their settlements had
appropriated. In this way Saracen armies, soon after the death of
Mohammed, Arabized the whole eastern and southern sides of the
Mediterranean from Syria to Spain, and Arab merchants set the stamp of
their language and religion on the coasts of East Africa as far as
Mozambique. The handful of Spanish adventurers who came upon the
relatively dense populations of Mexico and Peru left among them a
civilization essentially European, but only a thin strain of Castilian
blood. Thus the immigration of small bands of people sufficed to
influence the culture of that big territory known as Latin America.

Throughout the life of any people, from its fetal period in some small
locality to its well-rounded adult era marked by the occupation and
organization of a wide national territory, gradations in area mark
gradations of development. And this is true, whether we consider the
co