Why is western part of India a desert region?

The western part of India gets very less rainfall due to following reasons:

1. The Aravali's alignment is parallel to rain-bearing South-West Monsoon winds and as such they do not offer any obstruction. Furthermore, these hills are very low.
2. The moisture-laden winds passing over Rajasthan do not saturate as the heat in the desert region increases their capacity to hold moisture. Thus they reach Shivaliks without shedding their moisture.