The tarai is becoming indistinguishable from the plains as its environmental and cultural uniqueness is undermined. Traditionally, it was the place where transition from hill to plain took place.
Observers of the economic interaction between hill society and that of the plains tend to perceive the tarsi as supporting forms of socio-economic organisation which are representative of the plains. Insofar as the tarai has today almost ceased to exist, such a perception is not inexact. With an almost relentless momentum, the "plains" (more importantly, the kind of society and economy they support) have in many areas and in a series of waves advanced right up to the northern foothills. This phenomenon, however, is recent.
Some early descriptions of the tarai make interesting reading. Tavernier, a French merchant, who travelled through much of India in the mid-17th century describes the area lying to the north of Gorakhpur thus:
From Gorakhpur to the foot of the high mountains there are still eight or nine days' marching, during which the caravan suffers much, because the whole country is full of forests, where there are numerous wild elephants, and the merchants instead of sleeping at night must remain on the watch, making large fires and firing their muskets to frighten these animals."