The Hindu Kush, made famous by Alexander the Great during his conquering-travels east, is the main mountain range of Afghanistan. In the map above, it is depicted by the black circle in south-central Asia. Click on the image for a more distinctive view of the black circle (which appears white as displayed here).
Descriptively, the Hindu Kush can also be viewed as a western extension of the Karakoram Range (where K-2, the world's second-highest peak is located) and the western Himalayas. (See Figure 2.8 - "The Himalaya-Karakorum-Hindu Kush mountains" - at page 74 of of Mountain Environments and Communities, by Don Funnell and Ramola Parish.)
What does the name "Hindu Kush" mean? According to the Encyclopedia of World Geography, Volume 1 (edited by R. W. McColl):
The origin of the term Hindu Kush (which translates as "Hindu Killer" or "Killer of Hindus") is a point of controversy among scholars. Three possibilities have been put forward in this context.
One, the mountains concerned are tribute to Indian slaves who perished in the difficult mountainous terrain while being transported from India to slave markets of Central Asia. Two, the name is merely a corruption of Hindu Koh, the pre-Islamic name of the mountains that divided Hindu-populated southern Afghanistan from non-Hindu northern Afghanistan. The third possibility is that the name is a posited Avestan appellation meaning "water mountain."
How high are the mountain peaks in the Hindu Kush? The farther west, the lower the peaks:
Toward the middle near Afghanistan's capital city Kabul, they extend from 14,763 to 19,685 ft (4,500 to 6,000 m); in the west, they attain heights of 11,482 to 13,123 ft (3,500 to 4,000 m). The average altitude of the Hindu Kush mountain range stretches about 600 miles (966 km) laterally, and its median north-south measurement is about 149 miles (240 km).
Only about 373 miles (600 km) of the Hindu Kush system is called the Hindu Kush mountains. The rest of the system consists of numerous smaller ranges, including the Salang, Koh-e-Baba, Koh-e-Paghman, Spin Ghar, Sian Koh, Suleiman, Selseleh-e-band-e-Turkistan, and Koh-e-Khwaja Mohammad ... Three rivers flow from the Hindu Kush mountain range, namely the Helmand River, the Hari Rud, and the Kabul River that also provide water to major cities and regions of Afghanistan.
Mountain passes connect the Hindu Kush with other parts of Afghanistan:
Huge caravans pass through high passes (kotal) transecting the mountains. The most important mountain pass in the Hindu Kush range is the Kotal-e-Salang [Salang road], which links Kabul and points south to northern parts of Afghanistan.
Do people live in the area?
The Hindu Kush is sparsely populated and inhabitants subsist year-round on livestock and crops. The Kalash people are one of the main inhabitant groups of Hindu Kush and claim to be descendants of Alexander the Great. They have their own distinctive laws, religion and culture. (Encyclopedia of World Geography, Volume 1 - by R. W. McColl, Editor - pp 413-414 for all quotes above.)
Because of tectonic-plate activity, areas of the Hindu Kush have frequently endured earthquakes:
... epicenters of most twentieth-century activity seems to have shifted to north of Kabul in the Afghan Hindu Kush. The tectonic processes not only give these areas high hazard risk but also are the source of the abundant mineral resources for which mountains are renowned.
The earthquakes, in turn, cause other life-threatening events:
The earthquakes themselves may not be the greatest cause of damage. Most lives are lost as a result of the consequent landslides, mudflows, dam bursts [where dams exist] and fires in settled areas. The greatest problem in coping lies in the unpredictability of the earthquake event, and there are the additional problems of access due to poor weather, few places to land aircraft bringing supplies, and the frequency with which the single road in and out may be blocked or destroyed. (Mountain Environments and Communities, by Don Funnell and Romola Parish, page 131.)
In other words ... the mountains of the Hindu Kush are a beautiful, but dangerous, part of the world.
Quoted passages from various sources, noted above.