Why do high passes make travel across the central Hindu Kush difficult?

Travel across the central Hindu Kush is difficult primarily due to the extreme elevation of the mountain passes, which creates significant challenges for transmontane communication.1

In the central section of the range—stretching from the Dorāh Pass to the Shebar Pass—the terrain is characterized by a high concentration of summits that create an unbroken horizon, often referred to as Gipfelflur or "summit plain". Because these passes are situated at such high altitudes—with examples like the Verān and Rām Gol passes reaching approximately 15,400 feet (4,694 metres)—they present formidable physical barriers to travel. While modern infrastructure, such as the all-weather road through the Sālang Tunnel, has improved connectivity between northern and southern Afghanistan, the rugged, high-altitude nature of the central range historically necessitated reliance on difficult, high-altitude routes.123