Piedmont Plain lies between the foot of the Kumayun Himalaya and the Gangetic plain and includes two distinct belts of the country, each about ten to twenty five kilometres broad, known as the Bhabar and the Terai. Bhabar a narrow belt of the country is usually covered with forest and remarkable for the entire absence of water, a phenomenon eminently characteristic of this tract. Terai lies between the forest belt and the cultivated plains with varying breadths in different parts. This zone is characterised by the presence of reeds and grasses showing the marshy nature of the ground. The soil consists of moist alluvial matter without a sign of rock either in fragments or in site.

Sufficient information is not available to state distinctly how far the piedmont plain extends both east and west along the foot of the himalayas. Under Nepal it extends from the Kali to the Mechi on the east with the same general characteristics as under Kumayun. Eastward of the Tista the plain does not exhibit the same parallelism to the line of the Himalayas, but shows an irregular series of salient and resalient angles resting on the mountains. On the confines of Assam and Rangpur it is found in the plateau called the Parbat Joar, which is considerably elevated, quite insulated, remote from the mountains and covered with shal, the characteristic tree of the upper Bhabar. [ASM Woobaidullah]