The Cambridge History of India, Vol. I: Ancient India v1.c31.3

v1.c31.3

The Yavanas had come from Bactria over the Hindu Kush into the upper Kābul valley, and thence along the Kābul river into India by a route which has since been abandoned for that which now leads through the Khyber defile. It was formerly assumed that the Çakas came directly into India from the same region and by the same way. But this view is attended with difficulties which cannot be explained. In the first place, if the Çakas came through the Kābul valley, all traces of their invasion must be supposed to have disappeared from that region; for, among the many thousands of coins which were collected on its ancient sites at the time when the country was still open to archaeological investigation, the coins of the earliest Çaka kings are conspicuous by their absence; and secondly, it is certain that the Kābul valley remained in the possession of the Yavana princes of the house of Eucratides after the Yavana dominions in N.W. India on the eastern side of the Khyber Pass, that is to say, in Peshāwar and Rāwalpindi, had been conquered by the Çakas. Ingress from Bactria was therefore barred at this period.