Question

what would have been the climatic conditions of india if there were no northern mountain wall

Answer 1

If there were no northen mountain wall in India the summers become longer and the winter become shorter. But the winter became so powerful because of the presence of these mountains the cold air from the arctic do not reach India.

Answer 2

If there had been no Himalayas, all the rain bearing South-West Monsoon winds would have crossed india and into central Asia leaving India a desert. Mawsynram would not be the wettest place on earth. In fact it would have acute water shortage.

Moreover during the winter season, all the cold winds from Russia would reach India and freeze north India( for e.g. temperature in Beijing can dip to -20 °C in january where there is no such natural barrier).