Almost simultaneously with the invasions of the Avars we hear of the inroads of another tribe, the Bulgarians, who established a kingdom in the land between the Danube and the Hmmus—a land still called by their name. At various periods since that time the peoples in this land have asserted their freedom and raised Bulgarian kingdoms which have lasted many years, but the Bulgarians as well as the Avars, like the Normans in England, have been lost among the people whom originally they conquered.
In the ninth century another series of movements took place which, having their origin on the far steppes of Asia, materially affected European history. At the end of that century the Khazars coming from the east drove the Patzinaks from the district of the Volga, where they had appeared some fifty years earlier. These in turn drove another eastern people, the Magyars, farther to the west, so that again the Western world was disturbed by invasion. As usual, the advent of these Magyars or Hungarians was marked by raids, but in a com paratively short time an organized government was set up in that island of steppe within the Carpathians, Hungary, where the Magyars remain to this day, a people of Eastern descent yet received within the circle of nations which aim at Western ideals of civilization. The Patzinaks and Cumans, who had taken the place of the Magyars in Southern Russia, were up till the twelfth century a power to be reckoned with by the Empire on the Bosphorus, but have long since passed away.
In the thirteenth century the plain came under the rule of one man — the great Jenghiz Khan — and for three centuries his successors held sway to a greater or less extent over Central Asia, sending out armies which ravaged and subdued for shorter or longer periods the countries on the margins. In the thirteenth century Russia, Poland and Hungary were devastated by a general of the great Khan. Later, under the scarcely less famous Kublai Khan, Mesopotamia was conquered. In the fourteenth century Tamerlane ruled over a great part of Asia, and in the sixteenth a descendant of his invaded India and established the kingdom of the Great Moguls.
Finally, the Turks came by way of the steppeland of Asia Minor rather than by the gate between the Urals and the By the middle of the eleventh century they had gained control of all this area, and in a very few years—by the time of William the Conqueror—had added a considerable stretch of land to the south, in cluding Jerusalem. This caused the crusades to begin at this time, but otherwise did not affect European politics till much later. The power of the earlier ruling
house, the Seljuk Turks, was in fact much weakened by the Mongol raids on their eastern front in the thirteenth century, and it was only when the Ottoman Turks arose as a band who first served the Seljuks against the Mongols and then took the whole power to themselves, that advance towards Europe was continued. Though a large part of what was but lately Turkey in Europe fell into their hands by the middle of the fourteenth century, it was not till a century later, in 1453, that Constan tinople was at last taken and the Roman Empire finally came to an end. In the sixteenth century even Hungary came under Turkish rule, and remained so till the end of the seventeenth, when she again became free.
Thus we see as an ever-recurring phenomenon the emergence of peoples from the plain disturbing the settled folk on the margins, not only in Europe, be it noticed, but also in Western Asia, in India and in China. From prehistoric ages to within a few centuries of our own time the nomads of the plain have acted as a solvent on the fixed conditions of the people on the margins. To use a chemical metaphor, the process of crystallization has been retarded. The crystals already formed have been dissolved, but always after a while new crystals have formed to an even greater extent than before. Ever more and more geographical units have been occupied by fixed peoples with settled govern ments. Egypt, far removed from the plain, was little affected by the nomads, but, as we have seen, Assyria, Greece and Rome to an increasing extent were impelled to look in fear towards the mountains on their northward borders, from the defiles of which emerged peoples whose incentive to move was produced by the steppe conditions beyond. The Roman Empire was more exposed than the earlier powers to the incursions of these tribes, for her borders were carried north and eastward of the mountains on the south of Europe, and her frontiers lay open to attack far more than did the frontiers of the earlier empires. Thus it is that the later history of Rome is more intimately connected with the history of the peoples of the plain, that for centuries after stable states had formed in Western Europe the east was still open to forces from the steppe, and that the Eastern no less than the Western Empire was at length over thrown by the incursions of the steppe peoples.