The Cambridge History of India, Vol. I: Ancient India v1.c15.126

v1.c15.126

There are two lines, and only two, along which warlike invasions of N.W. India have been conducted in historical times. On the one hand the mountains become very narrow just north of the head of the Kābul river. There a single though lofty ridge, the Hindu Kush, is all that separates the basin of the Oxus from that of the Indus. Low ground, raised only a few hundred feet above the sea, is very near on the two sides of the Hindu Kush. There are several ways into India over this great but single range and down the Kābul valley. The most famous is known as the Khyber route, from the name of the last defile through which the track descends into the Indian plain.