How are mountains a safety barrier of India?

The Himalayas, due to their large size and expanse, have been a natural barrier to the movement of people for tens of thousands of years.

In particular, this has prevented intermingling of people from the Indian subcontinent with people from China and Mongolia, causing significantly different languages and customs between these regions.

The Himalayas have also hindered trade routes and prevented military expeditions across its expanse. For instance, Genghis Khan could not expand his empire south of the Himalayas into the subcontinent.

The Himalayas are the natural barriers on the north protecting the boundary from foreign occupation till today.