Question

classify himalayas on the basis of regions from west to east

Answer 1

This division of the Himalayas is demarcated by the river valleys.

Punjab Himalayas: This part of the Himalayas lies between the rivers Indus and Satluj. It is also known as Kashmir and the Himachal Himalayas.
Kumaon Himalayas: This part of the Himalayas lies between Satluj and Kali rivers.
Nepal Himalayas: This part of the Himalayas lies between Kali and Teesta rivers.

Answer 2

Himalayas can be classified of regions from West to East :
Punjab Himalayas: it lies between Indus and Sutluj

Kumaon Himalayas: it lies between Sutluj and Kali

Nepal Himalayas: it lies between Kali and Tista

Assam Himalayas: it lies between Tista and Dihang