Khyber Pass, the chief opening in the Khyber Mountains, begins 10 miles W. of Po.shnwnr, and extends 33 miles N.W. to the plain of Jelahibad. It is, the only route between the Punjab and Afghanistan available for nn army with baggage and artillery, and has afforded ingress or egress to numerous invaders from the time of Alexander the Great. The precipices on either side rise in some places to a. height of over 3,000 feet. It was here that a British army was in 1812 almost annihilated by the Afghans whilst retreating from Cabul. By the Treaty of Gandamak (1879) the British authorities in India now exercise control over the pass.