Explanation:

• Darjeeling and Sikkim Himalayas are famous for Duar formations. Duars are alluvial floodplains that lie south of the outer foothills of the Himalayas and north of the Brahmaputra River basin.
• This region is divided by the Sankosh River into Eastern and Western Duars. The Western Duars are also known as the Bengal Duars, and the Eastern Duars also as the Assam Duars.
• Duars is analogous with the Terai in northern India and southern Nepal.
• Duars play an important role in the region as they support the tea plantations.
• Significantly, The Shiwaliks are absent in this region.