In medieval times, the Himalayan mountain passes used to be the major trade routes of the South- Asian countries. The great Himalayan passes were the means through which a larger part of the Indian subcontinent along with Pakistan, Nepal, Bangladesh and Bhutan was connected to the rest of the world. In India, these routes were used for the trading of silk, spices and other goods. At present, these passes have immense military importance as a mode of supply for various military facilities such as food, fuel and ammunition. These high mountain passes play a major role in the growth of the tourism industry as major tourist destinations such as Ladakh, major areas in Uttarakhand, Himachal Pradesh and Sikkim are approachable through these high mountain passes. Not all high mountain passes are accessible for a regular tourist due to unfavorable weather conditions.