Wide digressions differentiate them still further from the parent stock by landing them amid different ethnic and social groups, by contact with whom they are inevitably modified.  The Namaqua Hottentots, living on the southern margin of the Hottentot country near the frontier of the European settlements in Cape Colony, acquired some elements of civilization, together with a strain of Boer and English blood, and in some cases even the Dutch vernacular.  They were therefore differentiated from their nomadic and warlike kinsmen in the grasslands north of the Orange River, which formed the center of the Hottentot area.[220] A view of the ancient Germans during the first five or six centuries after Christ reveals differentiation by various contacts in process along all the ragged borders of the Germanic area.  The offshoots who pushed westward across the Rhine into Belgian Gaul were rapidly Celticized, abandoning their semi-nomadic life for sedentary agriculture, assimilating the superior civilization which they found there, and steadily merging with the native population.  They became Belgae, though still conscious of their Teutonic origin.[221] The Batavians, an offshoot of the ancient Chatti living near the Thuringian Forest, appropriated the river island between the Rhine and the Waal.  There in the seclusion of their swamps, they became a distinct national unit, retaining their backward German culture and primitive type of German speech, which the Chatti themselves lost by contact with the High Germans.[222] Far away on the southeastern margin of the Teutonic area the same process of assimilation to a foreign civilization went on a little later when the Visigoths, after a century of residence on the lower Danube in contact with the Eastern Empire, adopted the Arian form of Christianity which had arisen in the Greek peninsula.[223] The border regions of the world show the typical results of the historical movement—­differentiation from the core or central group through assimilation to a new group which meets and blends with it along the frontier.

[Sidenote:  Geographic conditions of heterogeneity and homogeneity.]

Entrance into a naturally isolated district, from which subsequent incursions are debarred, gives conditions for divergence and the creation of a new type.  On the other hand, where few physical barriers are present to form these natural pockets, the process of assimilation goes on over a wide field.  Europe is peculiar among the family of continents for its “much divided” geography, commented upon by Strabo.  Hence its islands, peninsulas and mountain-rimmed basins have produced a variegated assemblage of peoples, languages and culture.  Only where it runs off into the monotonous immensity of Russia do we find a people who in their physical traits, language, and civilization reflect the uniformity of their environment.[224]