During the second millennium before our era successive waves of Nordics began to cross the Afghan passes into India until finally they imposed their primitive Aryan language upon Hindustan and the countries lying to the east. All those regions lying northwest of the mountains appear to have been largely a white man's country at the time of Alexander the Great. In Turkestan the newly discovered Tokharian language, an Aryan tongue of the western division, seems to have persisted down to the ninth century. The decline of the Nordics in these lands, however, began probably far earlier than Alexander's time, and must have been nearly completed at the beginning of our era. Such blond traits as are still found in western Asia are relatively unimportant, and for the last two thousand years these countries must be regarded as lost to the Nordic race. The impulse that drove the early Nordics like a fan over the Himalayan passes into India, the later Nordics southward into Mesopotamian lands, as Kassites, Mitanni, and Persians, into Greece and Anatolia as Achæans, Dorians, and Phrygians, westward as the Aryan-speaking invaders of Italy and as the Celtic vanguards of the Nordic race across the Rhine into Gaul, Spain, and Britain, may well have been caused by Mongoloid pressure from the heart of central Asia. Of course, we have no actual knowledge of this, but the analogy to the history of later migrations is strong, and the conviction is growing among historians that the impulse that drove the Hellenic Nordics upon the early Ægean culture world was the same as that which later drove Germanic Nordics into the Roman Empire. North of the Caspian and Black Seas the boundaries of Europe receded steadily before Asia for nearly a thousand years after our era opened, but we have scant record of the struggles which resulted in the eviction of the Nordics from their homes in Russia, Poland, the Austrian and east German lands. By the time of Charlemagne the White Man's world was reduced to Scandinavia, Germany west of the Elbe, the British Isles, the Low Countries, and northern France and Italy, with outlying groups in southern France and Spain. This was the lowest ebb for the Nordics and it was the crowning glory of Charlemagne's career that he not only turned back the flood, but began the organization of a series of more or less Nordicized marches or barrier states from the Baltic to the Adriatic, which have served as ramparts against Asiatic pressure from his day to ours. West of this line the feudal states of mediæval Europe developed into western Christendom, the nucleus of the civilized world of to-day. South of the Caspian and Black Seas, after the first swarming of the Nordics over the mountains during the second millennium before Christ, the East pressed steadily against Europe until the strain culminated in the Persian Wars. The defeat of Asia in these wars resulted later in Alexander's conquest of western Asia to the borders of India.