[Sidenote:  Diffusion of culture.]

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 new-comers.[141] 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 Mocambique.  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.

[Sidenote:  Ethnic intermixture.]

That vast sum of migrations, great and small, which we group under the general term of historical movement has involved an endless mingling of races and cultures.  As Professor Petrie has remarked, the prevalent notion that in prehistoric times races were pure and unmixed is without foundation.  An examination of the various forms of the historical movement reveals the extent and complexity of this mingling process.

In the first place, no migration is ever simple; it involves a number of secondary movements, each of which in turn occasions a new combination of tribal or racial elements.  The transference of a whole people from its native or adopted seat to a new habitat, as in the Voelkerwanderungen, empties the original district, which then becomes a catchment basin for various streams of people about its rim; and in the new territory it dislodges a few or all of the occupants, and thereby starts up a fresh movement as the original one comes to rest.

Nor is this all.  A torrent that issues from its source in the mountains is not the river which reaches the sea.  On its long journey from highland to lowland it receives now the milky waters of a glacier-fed stream, now a muddy tributary from agricultural lands, now the clear waters from a limestone plateau, while all the time its racing current bears a burden of soil torn from its own banks.  Now it rests in a lake, where it lays down its weight of silt, then