The Cambridge History of India, Vol. I: Ancient India v1.c31.6

v1.c31.6

Any direct invasion from the north seems, in fact, to be out of the question. It is therefore far more probable, nay almost certain, that the Çakas reached India indirectly, and that, like the Pahlavas, they came through Ariāna (W. and S. Afghānistān and Baluchistān) by the great highway, associated in modern times with the Bolān Pass, which led from the Parthian provinces of Drangiāna (Seistān) and Arachosia (Kandahār) over the Brāhūi mountains into the country of the lower Indus (Sind). This route was well known and comparatively easy. By it Craterus had returned with that division of Alexander’s army which included the elephants¹.