It is not yet quite clear how soon after the destruction of the Bactrian kingdom these Turanian tribes conquered Cabul, and occupied the country between that city and the Indus. Certain it is, however, that they were firmly seated on the banks of that river before the Christian Era, and under the great king Kanishka had become an Indian power of very considerable importance. The date of this king is, unfortunately, one of those small puzzles that still remain to be solved. Generally, it is supposed he reigned till about twenty to forty years after Christ.[24] Evidence, however, has lately been brought to light, which seems to prove that he was the founder of the Saka era, A.D. 79, and that his reign must be placed in the last quarter of the first century of our era, instead of in the earlier half.[25] Be this as it may, it seems quite certain that the power of these Turuska kings spread over the whole Punjab, and extended as far at least as Muttra on the Jumna, in the first century of the Christian Era. At the same time another horde, known to us only from the coins and inscriptions in which they call themselves Sahs or Sah kings, crossed the Indus lower down, and occupied the whole of the province of Gujerat. It is not quite clear whether the first of them, Nahapana, was only the Viceroy of one of these northern kings--probably of Kanishka himself--though he and his successors afterwards became independent, and founded a kingdom of their own. They seem to date their coins and inscriptions from the Saka era, A.D. 79, and the series extends from that date to A.D. 349, or at latest to 371.[26] It thus happens that though Gautamiputra, the Andra king (312-333), boasts of having humbled them,[27] they were only in fact finally disposed of by the rise of the Guptas. No other foreign race, so far as we know, seems to have crossed the Lower Indus into India. But the whole external history of northern India, from the time of Kanishka to that of Ahmed Shah Durani (1761) is a narrative of a continuous succession of tribes of Scythian origin, pouring across the Upper Indus into India, each more Turanian than the one that preceded it, till the whole culminated in the Mogul conquest of India, in the 15th century, by a people as distinct in blood from the Aryans as any that exist.