The Cambridge History of India, Vol. I: Ancient India v1.c15.148

v1.c15.148

The long barrier of the Hindu Kush seems as if it were designed by nature to be the protecting boundary of India on the north-west. It is the 'scientific frontier' which in the last century British policy sought in vain to secure. At the present time it lies mostly within the 'buffer state' of Afghānistān which was created as the best alternative. But there have been periods in history when it has formed the actual, as well as the ideal, limit of the Indian empire. In the last quarter of the fourth century B.C., within a few years of the departure from India of Alexander the Great, it separated the dominions of the Maurya emperor of India, Chandragupta, from those of Seleucus Nicator, Alexander's successor in the eastern portion of his vast empire. In about the middle of the third century B.C. the Seleucid province of Bactria, which lay immediately to the north of the Hindu Kush, became an independent kingdom, from which, when the Maurya empire declined and the barrier was no longer adequately protected, a second series of Greek invasions poured into India about 200 B.C.