Every country whose history we examine proves the recipient of successive streams of humanity. Even sea-girt England has received various intruding peoples, from the Roman occupation to the recent influx of Russian Jews. In prehistoric times it combined several elements in its population, as the discovery of the "long barrow" men and "round barrow" men by archaeologists and the identification of a surviving Iberian or Mediterranean strain by ethnologists go to prove. Egypt, Mesopotamia, and India tell the same story, whether in their recorded or unrecorded history. Tropical Africa lacks a history; but all that has been pieced together by ethnologists and anthropologists, in an effort to reconstruct its past, shows incessant movement—growth, expansion, and short-lived conquest, followed by shrinkage, expulsion, or absorption by another invader. To this constant shifting of races and peoples the name of historical movement has been given, because it underlies most of written history and constitutes the major part of unwritten history, especially that of savage and nomadic tribes.
Among primitive peoples this movement is simple and monotonous. It involves all members of the tribe, either in pursuit of game or following the herd over the tribal territory, or in migrations seeking more and better land. Among civilized peoples it assumes various forms and especially is differentiated for different members of the social group. The civilized state develops specialized frontiers—men, armies, explorers, maritime traders, colonists, and missionaries, who keep a part of the people constantly moving and directing external expansion, while the mass of the population converts the force once expended in the migrant food-quest into internal activity. Here we come upon a paradox. The nation as a whole, with the development of sedentary life, increases its population and therewith its need for external movements; it widens its national area and its circle of contact with other lands, enlarges its geographical horizon, and improves its internal communication over a growing territory; it evolves a greater mobility within and without, which attaches, however, to certain classes of society, not to the entire social group. This mobility becomes the outward expression of a whole complex of economic wants, intellectual needs, and political ambitions. It is embodied in the conquests which build up empires, in the colonization which develops new lands, in the world-wide exchange of commodities and ideas which lifts the level of civilization till this movement of peoples becomes a fundamental fact of history.
Otis Mason finds that the life of a social group involves a variety of movements characterized by different ranges or scopes: (1) The daily round from bed to bed. (2) The annual round from year to year, like that of the Tunguse Orochon of Siberia who, in pursuit of various fish and game, change their residence within their territory from month to month, or the pastoral nomads who move with the seasons from pasture to pasture. (3) Less systematic outside movements covering the tribal sphere of influence, such as journeys or voyages to remote hunting or fishing grounds, forays or piratical descents upon neighboring lands, eventuating usually in conquest, expansion into border regions for occasional occupation, or colonization. (4) Participation in streams of barter or commerce. (5) And, at a higher stage, in the great currents of human intercourse, experience, and ideas, which finally compass the world. In all this series the narrower movement prepares for the broader, of which it constitutes at once an impulse and a part.
Civilized man is at once more and less mobile than his primitive brother. Every advance in civilization multiplies and tightens the bonds uniting him with his soil, makes him a sedentary instead of a migratory being. On the other hand, every advance in civilization is attended by the rapid clearing of the forests, by the construction of bridges and interlacing roads, the invention of more effective vehicles for transportation whereby intercourse increases, and the improvement of navigation to the same end. Civilized man progressively modifies the land which he occupies, removes or reduces obstacles to intercourse, and thereby approximates it to the open plain. Thus far he facilitates movements. But while doing this he also places upon the land a dense population, closely attached to the soil, strong to resist incursion, and for economic reasons inhospitable to any marked accession of population from without. Herein lies the great difference between migration in empty or sparsely inhabited regions, such as predominated when the world 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 compass of their commercial exchanges, the scope of their maritime ventures, the extent of their linguistic area, the measure of their territorial ambitions, or the range of their intellectual interests and human sympathies. From land to ethics, the rule holds good. Peoples in the lower stages of civilization have contracted spatial ideas, desire and need at a given time only a limited territory, though they may change that territory often; they think in small linear terms, have a small horizon, a small circle of contact with others, a small range of influence, only tribal sympathies; they have an exaggerated conception of their own size and importance, because their basis of comparison is fatally limited. With a mature, widespread people like the English or French, all this is different; they have made the earth their own, so far as possible.
Just because of this universal tendency toward the occupation of ever larger areas and the formation of vaster political aggregates, in making a sociological or political estimate of different peoples, we should never lose sight of the fact that all racial and national characteristics which operate toward the absorption of more land and impel to political expansion are of fundamental value. A ship of state manned by such a crew has its sails set to catch the winds of the world.
Territorial expansion is always preceded by an extension of the circle of influence which a people exerts through its traders, its deep-sea fishermen, its picturesque marauders and more respectable missionaries, and earlier still by a widening of its mere geographical horizon through fortuitous or systematic exploration.