Question

How can you say that himalyan mountains are boon for India?

Answer 1

Because they block the rain bearing monsoon winds from the Arabian sea and the Bay of Bengal. Therefore, the North India plains receive plenty of rainfall.
There is lot of snowfall in the higher regions of the mountains. The snow melts in summer. The rivers like the Brahmaputra and Ganga which rise among these ranges are fed by the water of the melting snow. These rivers never dry up during the hot summer months. So, they protect India from the cold, biting winds blowing from North Asia. The winters of North India are milder than those beyond the mountains. These mountains with their higher peaks and ravines are difficult to cross. Therefore, they prevented many invaders from easily invading our country. Thus, the role of Himalayas as a guard of Northern boundary is very important.
The Himalayan rivers bring rich silt from the mountains and deposit in the plains below. This silt has made the northern plains very fertile. There are thick forests on the Himalayas. They supply us with valuable honey, medicinal herbs, timber, wax, etc. They also provide a home to innumerable birds and animals.