What physical feature gave the Indus Valley natural protection

The Himalayan Mountains gave natural protection to the Indus Valley.

Explanation:

The Indus Valley is a river valley that was home to one of the first civilizations in the world, the Indus Valley civilization. This civilization developed independently from the other civilizations in its time, and the reason for this was its relative isolation from them. The isolation came because of the Himalayan Mountains.

The Himalayan Mountains are the highest mountain range in the world, and they act as a natural barrier between most of the Indian subcontinent and the rest of Asia. This relative isolation has led to the development of unique culture, much more egalitarian and peaceful than the other ones of that period. Also, this high mountain range was guaranteeing safety when it came to facing invasions, so the people of this civilization were able to live in a relatively relaxed manner and feel safe.