This Parthian dynasty was then followed in the Indian empire after a short interval by what is designated in Indian tradition as that of the Sacae or that of king Kanerku or Kanishka, which begins with A.D. 78 and subsisted at least down to the third century.[19] They belong to the Scythians, whose immigration was formerly mentioned, and on their coins the Scythian language takes the place of the Indian.[20] Thus in the region of the Indus, after the Indians and the Hellenes, Parthians and Scythians bore sway in the first three centuries of our era. But even under the foreign dynasties a national Indian type of state was established and held its ground, and opposed a not less permanent barrier to the development of the Partho-Persian power in the East than did the Roman state in the West. [Sidenote: Asiatic Scythians.] Towards the north and north-east Iran bordered with Turan. As the western and southern shores of the Caspian Sea and the upper valleys of the Oxus and Jaxartes offered an appropriate seat for civilisation, so the steppe round the Sea of Aral and the extensive plain stretching behind it belonged by right to the roving peoples. There were among those nomads probably individual tribes kindred to the Iranians; but these have no part in the Iranian civilisation, and it is this element which determines the historical position of Iran, that it forms the bulwark of the peoples of culture against those hordes, who, as Scythians, Sacae, Huns, Mongols, Turks, appear to have no other destiny in the world’s history than that of annihilating culture. Bactria, the great bulwark of Iran against Turan, sufficed for this defence during a considerable time under its Greek rulers in the epoch after Alexander; but we have already mentioned that subsequently, although it did not perish, it no longer availed to prevent the Scythians from pressing onward towards the south. With the decay of the Bactrian power the same task was transferred to the Arsacids. How far they responded to it it is difficult to say. In the first period of the empire the great-kings of Ctesiphon seem to have driven back the Scythians or to have brought them into subjection in the northern provinces as well as to the south of the Hindoo Koosh; they wrested from them again a portion of the Bactrian territory. But it is doubtful what limits were here fixed, and whether they were at all lasting. There is frequent mention of wars between the Parthians and Scythians. The latter, here in the first instance dwellers around the Sea of Aral, the forefathers of the modern Turkomans, are regularly the aggressors, inasmuch as they partly by crossing over the Caspian Sea invade the valleys of the Cyrus and the Araxes, partly issuing from their steppes pillage the rich plains of Hyrcania and the fertile oasis of Margiana (Merv). The border-regions agreed to buy off the levy of arbitrary contributions by tributes, which were regularly called up at fixed terms, just as at present the