Солтүстік Үндістан мен Оңтүстік Непалдың жазық аймағы

Region in northern India and southern Nepal

The Terai or Tarai is to a lowland region in parts of northern India and southern Nepal that lies to the south of the outer foothills of the Himalayas, the Sivalik Hills and north of the Indo Gangetic Plain. This lowland belt is characterised by tall grasslands, scrub savannah, sal forests and clay rich swamps. In North India, the Terai spreads from the Yamuna River eastward across Haryana, Uttarakhand, Uttar Pradesh, Bihar and West Bengal. The Terai is part of the Terai Duar savanna and grasslands ecoregion. Nepal's Terai stretches over , about 23.1% of Nepal's land area, and lies at an elevation of between The region comprises more than 50 wetlands. North of the Terai rises the Bhabar, a narrow but continuous belt of forest about wide.

The Urdu word ترائی tarāʼī means "lands lying at the foot of a watershed" or "on the banks of a river; low ground flooded with water, valley, basin, marshy ground, marsh, swamp; meadow". In Hindi, the region is called तराई 'tarāī' meaning "foot hill". In Nepali, the region is called तराइ 'tarāi' meaning "the low lying land, plain" and especially "the low lying land at the foot of the Himālayas". It has been described as "low, marshy ground".

The Terai is crossed by the large perennial Himalayan rivers Yamuna, Ganges, Sarda, Karnali, Narayani and Kosi that have each built alluvial fans covering thousands of square kilometres below their exits from the hills. Medium rivers such as the Rapti rise in the Mahabharat Range. The geological structure of the region consists of old and new alluvium, both of which constitute alluvial deposits of mainly sand, clay, silt, gravels and coarse fragments. The new alluvium is renewed every year by fresh deposits brought down by active streams, which engage themselves in fluvial action. Old alluvium is found rather away from river courses, especially on uplands of the plain where silting is a rare phenomenon. A large number of small and usually seasonal rivers flow through the Terai, most of which originate in the Sivalik Hills. The soil in the Terai is alluvial and fine to medium textured. Forest cover in the Terai and hill areas has decreased at an annual rate of 1.3% between 1978 and 1979, and 2.3% between 1990 and 1991.

Based on the Köppen–Geiger climate classification system, the Nepal Terai experiences a tropical savanna climate type with dry winters and hot summers, a mean annual temperature of , a mean annual rainfall of in the west and in the east.

Tharu and Dhimal people are the indigenous inhabitants of the Terai forests. Several Tharu subgroups are scattered over most of the Nepal and Indian Terai. They used to be semi nomadic, practised shifting cultivation and collected wild fruits, vegetables and medicinal herbs. They have been living in the Terai for many centuries and reputedly had an innate resistance to malaria. Dhimal reside in the eastern Nepal Terai, viz Sunsari, Morang and Jhapa Districts. In the past, they lived in the fringes of the forest and conducted a semi nomadic life to evade outbreaks of diseases. Today, they are subsistence farmers. Following the malaria eradication program using DDT in the 1960s, a large and heterogeneous non Tharu population settled in the Nepal Terai. Several Chepang people also live in Nepal's central and eastern Terai districts. As of June 2011, the human population in the Nepal Terai totalled 13,318,705 people in 2,527,558 households comprising more than 120 different ethnic groups and castes such as Badi, Chamling, Ghale, Kumal, Limbu, Magar, Muslim, Rajbanshi, Teli, Thakuri, Yadav and Majhi speaking people.

The Muslim invasion of northern India during the 14th century forced Hindu and Buddhist people to seek refuge from religious persecution. Rajput nobles and their entourage migrated to the Himalayan foothills and gained control over the region from Kashmir to the eastern Terai during the following three centuries. By the 16th century, the rulers of Palpa and Makwanpur controlled the mid western Terai and extended this control to the eastern Terai by the 17th century. They controlled the area of today's districts of Saptari, Siraha, Dhanusa, Mahottari and Sarlahi. The rulers of Makwanpur controlled the central Terai region of present day Nepal, and the rulers of Vijayapur controlled today's Sunsari, Morang and Jhapa Districts. The Shah dynasty conquered the eastern Nepal Terai in the 1770s. They also conquered land in the eastern Terai that belonged to the Kingdom of Sikkim. The Tulsipur State, in the Dang Valley of Nepal's western Terai, was also an independent kingdom until it was conquered in 1785 by Bahadur Shah of Nepal during the unification of Nepal. Until the mid 18th century, the Nepal Terai was divided into several smaller kingdoms, and the forests and wild places were, largely, left undisturbed. Since the late 18th century, however, the Shah rulers encouraged Indians to settle in the Terai, and supported famine stricken Bihari farmers in efforts to convert to a more productive agricultural lifestyle in the eastern Nepal Terai. From at least 1786 onward, they appointed government officers in the eastern Terai districts of Parsa, Bara, Rautahat, Mahottari, Saptari and Morang to levy taxes, collect revenues and maintain civil order, as well as to hunt wild game, including Indian elephants and Indian rhinoceros, mostly for their ivory. At the end of the 18th century, between 200 and 300 elephants were caught annually, using snares or nooses. The far western and mid western regions of the Nepal Terai (called 'Naya Muluk', or ‘new country’) lay on the northern periphery of the Awadh dynasty. After Nepal lost the Anglo–Nepalese War of 1816, the British annexed these regions of the Terai when the Sugauli Treaty was ratified; as a reward for Nepal's military aid in the Indian Rebellion of 1857, they returned some of this region in 1860, namely today's districts of Kanchanpur, Kailali, Banke and Bardiya. To promote economic development of the Nepal Terai, people from the hills were invited to settle in the region. Since only a few moved to the Terai, Indian people were further encouraged to settle. Immigration of Indian people increased between 1846 and 1950. Dacoit gangs retreated to the Terai jungles, and the area was considered lawless and wild by the British, who sought control of the region's valuable timber reserves. The region was densely forested with stands of foremost Sal. Inner Terai valleys historically were agriculturally productive but extremely malarial. Some parts were left forested by official decree during the Rana dynasty as a defensive perimeter called Char Kose Jhadi, meaning 'four kos forest'; one kos equals about A British observer noted, "Plainsmen and paharis generally die if they sleep in the Terai before November 1 or after June 1." British travelers to Kathmandu went as fast as possible from the border at Raxaul to reach the hills before nightfall. About 16,000 Tibetan refugees settled in the Nepal Terai in 1959–1960, followed by refugees of Nepali origin from Burma in 1964, from Nagaland and Mizoram in the late 1960s, and about 10,000 Bihari Muslims from Bangladesh in the 1970s. Timber export continued until 1969. In 1970, King Mahendra granted land to loyal ex army personnel in the districts of Jhapa, Sunsari, Rupandehi and Banke Districts, where seven colonies were developed for resettling about 7,000 people. They acquired property rights over uncultivated forest and 'waste' land, thus accelerating the deforestation process in the Terai. Since the 1990s, migration from the Terai to urban centres is increasing and causing sociocultural changes in the region.

Since the early 1950s, several political parties advocated for autonomy and independence of the Nepal Terai, such as the Nepal Terai Congress and Janatantrik Terai Mukti Morcha. Several armed groups were formed, which pursued this aim using violent means. In 2013, more than 24 Madheshi political parties were registered for the Constituent Assembly of Nepal election.

The most significant border dispute of the Indo Nepal boundary in the Terai region is the Susta area. In the Susta region, 14,500 hectares of land is under dispute but recent development has manage to discuss it bilaterally.

After the 2008 Nepalese Constituent Assembly election, Indian politicians kept on trying to secure strategic interests in the Nepal Terai, such as over hydropower energy, development projects, business and trade. The government of Nepal has accused India of imposing an undeclared blockade in 2015 but it is not clear yet, local peoples blame Nepal administration and government.

Dhurmus Suntali Foundation handed over an integrated community containing 50 houses to Musahar community of Bardibas at a cost of Rs. 63 million.

The Terai is the most productive region in Nepal with the majority of the country's industries. Agriculture is the basis of the economy. Major crops include rice, wheat, maize, potato, peas, lentil, mustard, sugar cane, ginger, turmeric, cardamom, garlic and chili. Fruits comprise mango, lychee, guava, papaya, banana and jackfruit. The Terai is also known for beekeeping and honey production, with about 120,000 colonies of Apis cerana. In Jhapa District, tea has been cultivated since 1960; the annual production of 2005 was estimated at 10.1 million kg. The Mahendra Highway crosses the Nepal Terai from Kankarbhitta on the eastern border in Jhapa District, Province No. 1 to Mahendranagar near the western border in Kanchanpur District, Mahakali Zone. It is the only motor road spanning the country from east to west.

Tea cultivation was introduced in the Darjeeling Terai in 1862.