Note 154 — Chapter IV · —The Movements Of Peoples In Their Geographical Significance

Every aggressive historical movement, whether bold migration or forcible extension of the home territory, involves displacement or passive movement of other peoples (except in those rare occupations of vacant lands), who in turn are forced to encroach upon the lands of others. These conditions involve war, which is an important form of the historical movement, contributing to new social contacts and fusion of racial stocks. Raids and piratical descents are often the preliminary of great historical movements. They first expand the geographical horizon, and end in permanent settlements, which involve finally considerable transfers of population, summoned to strengthen the position of the interloper. Such was the history of the Germanic invasions of Britain, the Scandinavian settlements on the shores of Iceland, Britain, and France, and the incursions of Saharan tribes into the Sudanese states. Among pastoral nomads war is the rule; the tribe, a mobilized nation, is always on a war footing with its neighbors. The scant supply of wells and pasturage, inadequate in the dry season, involves rivalry and conflict for their possession as agricultural lands do not. Failure of water or grass is followed by the decline of the herds, and then by marauding expeditions into the river valleys to supply the temporary want of food. When population increases beyond the limits of subsistence in the needy steppes, such raids become the rule and end in the conquest of the more favored lands, with resulting amalgamation of race and culture.154