Dang valley

Dang-Deukhuri District (Nepali: दाङ-देउखुरी जिल्ला) is an Inner Terai district some 280 km west of Kathmandu in Rapti Zone ofNepal's Mid-Western Region. Dang-Deukhuri covers an area of 2,955 km² with population (2001) of 462,380. Tribhuwannagar(usually called Ghorahi) is the district's administrative center.

This district consists of the larger easterly and upstream portions of parallel Inner Terai valleys, Dang and Deukhuri, plus enclosing ranges of hills and mountains. Downsteam, both valleys cross intoBanke District, Bheri Zone.
To the south, the district adjoins Balarampur and Shravasti districts ofUttar Pradesh state, India. The international border follows the southern edge of the outermost Siwalik foothills called the Dunduwa Range so there is no Nepalese Outer Terai extending onto the main Ganges Plain. The permeable geology of the Siwaliks does not support moisture retention or soil development so they are covered with unproductive scrub forest and function as a buffer zone between markedly different cultures of the Inner and Outer Terai.
The Dunduwas rise steeply to a crest at about 700 meters then slope down gradually into Deukhuri Valley, to 250 meters at the Rapti River. The Dunduwas extend more than 100 km, causing the Rapti to detour west around them before turning SE down the overall trend of the plains. Deukhuri's climate is fully tropical and it is well watered by the river as well as abundant groundwater. It was severely malarial before the 1960s when DDT came into use to suppress mosquitos so that Tharu people who had evolved resistance were able to live in relative isolation from more developed and avaricious cultures of the plains to the south and the hills to the north. Since the early 1990s activist groups have been attempting to eradicate the practice of child indentured servitude among the Tharu, many of whom sold young daughters to wealthy families in urban areas. 
Mahendra Highway -- the main east-west highway across Nepal -- follows Deukhuri Valley, passing Bhalubang bazar at the upper end and Lamahi downstream. Branch roads lead up the Rapti River into Pyuthan and Rolpa Districts, north across the Dang Range to Tulsipur and Tribuvannagar, and south over the Dunduwas to Koilabas bazaar on the international border where goods enter Rapti Zone from India. Although the highway has ended Deukhuri's isolation, the valley retains some of its Garden of Eden charm with its lazy river, thick jungle alternating with rice paddies, surrounding hills in the middle distance, and unique peoples. It is quite different from the "hills" to the north and the plains to the south in many respects.
North of Deukhuri Valley the Dang Range rises to peaks as high as 1,000 meters with passes at about 700 meters. Dang Valley lies north of these hills, at elevations from 600 meters along the Babai River with alluvial slopes gradually rising northward to 700 meters along the base of the Mahabharat Range. Dang is higher, less tropical, drier and less malarial than Deukhuri. Despite poorer soil and more seasonal streamflow, its healthier climate made it more attractive to settlers from outside and left the indigenous Tharu population more vulnerable to exploitation even before the arrival of DDT.
All-weather Tribhuvannagar Airport has scheduled connections to other cities in Nepal. Besides road connections south to Deukhuri Valley as mentioned above, there are motorable roads north into Salyan and Pyuthan Districts.
North of Dang Valley, the district extends upslope to the crest of the Mahabharats at 1,500 to 1,700 meters elevation, but this slope is steep and virtually uninhabited, another cultural buffer zone. Bordering districts to the north are Pyuthan, Rolpa and Salyan. This crest marks the beginning of the culturally distinct Middle Hills where Nepali is the dominant language, the homeland of Nepal's politically dominant Bahuns and Chhetris.