In fact, one of those occasions of peril had arisen, to which in ancient times the civilized world was always liable from an outburst of northern barbarism. Whether the peril has altogether passed away or not we need not here inquire; but certainly in the old world there was always a chance that civilization, art, refinement, luxury, might suddenly and almost without warning be swept away by an overwhelming influx of savage hordes from the unpolished North. From the reign of Oyaxares, when the evil first showed itself, the danger was patent to all wise and far-seeing governors both in Europe and Asia, and was from time to time guarded against. The expeditions of Cyrus against the Massagetse, of Darius Hystaspis against the European Scyths, of Alexander against the Getee, of Trajan and Probus across the Danube, were designed to check and intimidate the northern nations, to break their power, and diminish the likelihood of their taking the offensive. It was now more than four centuries since in this part of Asia any such effort had been made; and the northern barbarians might naturally have ceased to fear the arms and discipline of the South. Moreover the circumstances of the time scarcely left them a choice. Pressed on continually more and more by the newly-arrived Su and Yue-chi, the old inhabitants of the Transoxianian regions were under the necessity of seeking new settlements, and could only attempt to find them in the quarter towards which they were driven by the new-comers. Strengthened, probably, by daring spirits from among their conquerors themselves they crossed the rivers and the deserts by which they had been hitherto confined, and advancing against the Parthians, Bactrians, and Arians, threatened to carry all before them. We have seen how successful they were against the Bactrians. In Ariana, they passed the mountains, and, proceeding southwards, occupied the tract below the great lake wherein the Helmend terminates, which took from them the name of Saeastane (“land of the Saka,” or Scyths)--a name still to be traced in the modern “Seistan.” Further to the east they effected a lodgment in Kabul, and another in the the southern portion of the Indus valley, which for a time bore the name of Indo-Scythia. They even crossed the Indus and attempted to penetrate into the interior of India, but here they were met and repulsed by a native monarch, about the year B.C. 56.