1. It is amazing that even we don't know, the Himalayas greatly influence the weather and climate of the South Asian countries such as Bangladesh, India, Nepal, Bhutan, etc. This is how it happens:

The land north of the Himalayas is extremely cold and windy. The Himalayas stand as a great barrier or wall and prevent the cold winds from blowing into the subcontinental countries. 

The Himalayas help rainfall in the subcontinent.

* The snow in the mountains melts in the summer and fills the rivers of India and Bangladesh. Many of the east and north rivers of the subcontinent are snow-fed rivers. Because of this, our rivers have water in the hottest summer months.
2. The Alps - the longest mountain range, as per my observation, is another example of a geoenvironmental divide.
The River Rhône forms a clear boundary between the Alps from the Massif Central.