Terai in Nepal
In Nepal, Terai is differentiated into "Outer" and "Inner" Terai.
Outer Terai or Madhes begins at the southern edge of the Siwalik Hills. In ordinary usage the Terai extends to the border with India, even if drier, cleared agricultural land well south of the marshes may be included. The Outer Terai of far-western Nepal consists of Kanchanpur, Kailali, Bardiya and Banke districts. These were once called the Naya Muluk and lay on the periphery of the Awadh dynasty. After Nepal lost the Anglo–Nepalese War (1814–16) these districts were annexed by the British in the Sugauli Treaty and returned in 1860 as reward for Nepal's military aid in the Indian Rebellion of 1857.
East of Banke the Nepalese outer Terai is interrupted where the international border swings north and follows the edge of the Siwaliks adjacent to Deukhuri Valley. Here the Outer Terai is entirely in Uttar Pradesh's Shravasti and Balrampur districts. East of Deukhuri the international border extends south again and Nepal has three more Outer Terai districts Kapilvastu, Rupandehi and Nawalparasi.
In Chitwan district east of Nawalparasi the international border again follows the southernmost Siwaliks, placing the outer Terai in Bihar's West Champaran district. Then the international border extends south and the Nepalese Outer Terai is continuous across eleven districts to the country's eastern border. These additional districts are: Parsa, Bara, Rautahat, Sarlahi, Mahottari, Dhanusa, Siraha, Saptari, Sunsari, Morang and Jhapa.
The 2001 national census counted 10.3 million population (45% of the national total) in the outer Terai districts.
Read more about this topic: Terai