It was by no means their first entrance on the stage of history. We believe that the dominant races of historical Greece, and perhaps of historical Rome, traced back their ancestry to the central regions of Europe. Since then history had recorded several alarming incursions of northern barbarians, and in a general sense the story of the Mediterranean peoples shows how wave after wave of strong warriors from the North descended upon the fertile peninsulas of the South, which always absorbed and assimilated them, until finally they became a prey to the enervating influences of climate, melted into the native strain, and had to make room for a fresh wave of untamed northerners. Read in this light, extraordinary interest attaches to the moment when all-conquering Rome attempted to conquer the wilds which sheltered these mighty tribes. If she had succeeded in taming and Romanising the Germans also, as she had done with the Spaniards and Gauls, the course of history might have been very different. But even then, though she knew it not, behind the Teutonic peoples lay the Slavs, and behind them the Tartars and the Huns. The task of civilising the world from a single centre was impossible. Augustus would have been wiser to choose a strong frontier first and then proceed gradually by peaceful penetration. Probably Augustus judged that the policy of buffer states which he had applied in the East was not applicable to barbarians. As it was, conquest was the method he selected, contrary to his usual custom and contrary to his natural inclination. Herein success led to over-confidence and so to disaster.