Explanation:

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Assam Himalaya is a traditional designation for the portion of the Himalaya range between the eastern border of Bhutan, on the west, and the Great Bend of the Tsangpo River, on the east.
Western Himalaya refers to the western half of the Himalayas, stretching from Badakhshan in northeastern Afghanistan/southern Tajikistan, Pakistan through North India Jammu and Kashmir, Ladakh and Himachal Pradesh. It is also known as Punjab Himalaya.
Kumaon or Kumaun is one of the two regions and administrative divisions of the Indian state of Uttarakhand, the other being Garhwal. It includes the districts of Almora, Bageshwar, Champawat, Nainital, Pithoragarh, and Udham Singh Nagar. It is bounded on the north by Tibet, on the east by Nepal, on the south by the state of Uttar Pradesh, and on the west by the Garhwal region. The people of Kumaon are known as Kumaonis and speak the Kumaoni language.
The part of the Himalayas lying between the rivers Kali and Teesta is known as Nepal Himalayas.