Hindu Kush, great mountain system of Central Asia. Broadly defined, it is some 500 miles (800 km) long and as wide as 150 miles (240 km).
The Hindu Kush is one of the great watersheds of Central Asia, forming part of the vast Alpine zone that stretches across Eurasia from east to west. It runs northeast to southwest and divides the valley of the Amu Darya (the ancient Oxus River) to the north from the Indus River valley to the south. To the east the Hindu Kush buttresses the Pamir range near the point where the borders of China, Pakistani-controlled Kashmir, and Afghanistan meet, after which it runs southwest through Pakistan and into Afghanistan, finally merging into minor ranges in western Afghanistan. The highest peak is Mount Tirich Mir, which rises near the Pakistan-Afghanistan border to 25,230 feet (7,690 metres).
It was through the high passes of the Hindu Kush in about 1500 BC that invaders from Central Asia brought their Indo-European language—a forerunner of the Indo-Iranian languages spoken throughout the region today. Historically, the passes have been of great military significance, providing access to the northern plains of India for such conquerors as Alexander the Great, the king of Macedonia; the Mongols Genghis Khan and Timur (Tamerlane); and their descendant Babur, the first Mughal emperor. During the period of British rule in India, the Indian government was keenly concerned with the security both of these passes and of an associated physical feature to the south, the Khyber Pass. The Hindu Kush range has rarely constituted the frontier between major powers but has usually formed part of an intermediate buffer zone. The name Hindu Kush derives from the Arabic for “Mountains of India.” Its earliest known usage occurs on a map published about AD 1000.