The Asiatic steppes had long teemed with a nomadic population, of a war-like temper, and but slightly attached to its homes, which ignorance of its own strength and of the weakness and wealth of its neighbors had alone prevented from troubling the great empires of the South.

Geographic difficulties had at once prolonged the period of Ignorance, and acted as obstructions, if ever the idea arose of pushing exploring parties into the southern regions; the Caucasus, the Caspian, the sandy deserts of Khiva and Kharesm, and the great central Asiatic mountain-chains, forming barriers which naturally restrained the northern hordes from progressing in this direction.

But a time had now arrived when these causes were no longer to operate; the line of demarcation which had so long separated North and South was to be crossed; the flood-gates were to be opened, and the stream of northern emigration was to pour itself in a resistless torrent over the fair and fertile regions from which it had hitherto been barred out.

Perhaps population had increased beyond all former precedent; perhaps a spirit of enterprise had arisen; possibly some slight accident--the exploration of a hunter hard pressed for food, the chattering tongue of a merchant, the invitation of a traitor--may have dispelled the ignorance of earlier times, and brought to the knowledge of the hardy North the fact that beyond the mountains and the seas, which they had always regarded as the extreme limit of the world, there lay a rich prey inviting the coming of the spoiler.
The condition of the northern barbarians, less than two hundred years after this time, has been graphically portrayed by two of the most observant of the Greeks, who themselves visited the Steppe country to learn the character and customs of the people.

Where civilization is unknown, changes are so slow and slight, that we may reasonably regard the descriptions of Herodotus and Hippocrates, though drawn in the fifth century before our era, as applying, in all their main points, to the same race two hundred years earlier.