The recorded movements of peoples in historic times, and the previous movements inferred from language, and other symptoms, indicate a long-established distribution of what might be described in meteorological phrase as _man-pressure_; certain regions being characterized either always or repeatedly by high man-pressure, and an outward flow of men into the cyclonic areas or vortexes of low man-pressure in the human covering (or biosphere) of the planet. Typical high-pressure regions are the Arabian peninsula with its repeated crises of Semitic eruption, and the great Eurasian grasslands. Typical regions of low man-pressure, and repeated irruption, are the South European peninsulas. Occasionally a region plays both parts, alternately accepting inhabitants, and unloading them on to other lands; examples are the Hungarian plain, Scandinavia, and Britain. Others again can hardly be said to have a population of their own at all, but are simple avenues of transmission, like Western Switzerland and the Hellespont Region. I am speaking now, of course, about ancient times. The causes of these recurrent movements are not clearly made out; but the movements themselves, and the fact that they are of regional recurrence, are matters of history. Conspicuous among such movements are the westward drift from Asia into peninsular Europe, in its three parallel columns, through tundra, forest, and steppe; and the southward drifts, subsidiary to this, from East Central Europe into the Balkan lands and round the head of the Adriatic. The course of these drifts is laid out in detail, as we have seen, by the physique of the regions; and therewith is determined the kind of life which each set of folk must be living if it is to survive the journey.