Diplomatically sealed by China and India after the 1962 Sino-Indian War, the pass saw skirmishes between the two countries in coming years, including the clashes in 1967 which resulted in fatalities on both sides.

The opening of the pass provides an alternative route to the pilgrimage of Mount Kailash and Lake Manasarovar, and was expected to bolster the economy of the region by playing a key role in the growing Sino-Indian trade.

[18] Lepcha people who are native to the region call it ma-tho hlo/na tho lo; which may have possibly evolved to the present usage of the word.

Nathu La is a mountain pass on the Dongkya Range that separates Sikkim and the Chumbi Valley at an elevation of 14,250 feet (4,340 m).

In 1873, J. W. Edgar, the Deputy commissioner at Darjeeling, was asked to investigate the trading conditions and make recommendations for a preferred route.

[29] Edgar wrote, On the whole, I am not inclined to recommend that Guntuck [Gangtok] should be chosen for the mart, and rather think that ... Dumsong [Damsang] might be preferable to any of the lower elevations of Sikhim.

[30]In 1903–04 Francis Younghusband led a British military expedition into Lhasa consisting of 1,150 soldiers and over 10,000 support staff and pack animals.

[34][35] Chapman writes that during their journey from Gangtok to Nathu la, just at the foot of the pass, was a road leading to the right and a signbord indicating Kupup.

[38] At the summit, Chapman writes of groups of stones and prayer flags these were not only for the protection of travelers, but they marked the boundary between Sikkim and Tibet.

[39] In 1938–39 Ernst Schäfer led a German expedition to Tibet legally via Nathu La on the orders of Heinrich Himmler.

[46] The Dalai Lama, Tenzin Gyatso, used this pass to travel to India for the 2,500th birthday celebration of Gautama Buddha, in the autumn of 1956.

[56] At Nathu La, differing perceptions of the Line of Actual Control among frontline troops on both sides factored in to the increasing tensions.

[61] China, however, refused to acknowledge the accession,[62] but the two armies continued to maintain informal communication at the border despite the freeze in diplomatic relations.

[64] In 2003, with the thawing of Sino-Indian relations, Indian Prime Minister Atal Bihari Vajpayee's visit to China led to the resumption of talks on opening the border.

[66][67] In August 2003, the Chief Minister of Sikkim Pawan Chamling shook hands with a PLA soldier along the border and followed it up by giving his wristwatch.

[78] Harris explains that this narrative of Nathu La rather highlighted the "contemporary global discourse"—that of a globalising and inter-connected Asia finding its place in the world, of which Sikkim and Chumbi Valley were a part.

Vegetation he listed included species of Caltha scaposa, Cochlearia, Potentilla, Saussurea, Rhododendron, Cassiope, Primula, Corydalis, Arenaria, Saxifraga, Chrysosplenium, Pimpinella, Cyananthus, Campanula, Androsace, Eritrichium, Lagotis and Salvia.

[97] The nearby Kyongnosla Alpine Sanctuary has rare, endangered ground orchida and rhododendrons interspersed among tall junipers and silver firs.

The mixed hunting species present in the region include warblers, tit-babblers, treecreepers, white-eyes, wrens, and rose finches.

Upon return, silk, raw wool, musk pods, medicinal plants, country liquor, precious stones, gold, and silverware were imported into India.

[101] The informal group, consisting of civil servants and trade experts, was headed by Mahendra P. Lama and submitted its report in 2005.

[104] India's Confederation of Indian Industry (CII) gave an even higher estimation that trade could cross USD 10 billion in a decade.

[110] In 2008, Mahendra P. Lama commented upon the mismatch in projections and actual trade during the first two years, "this is mostly attributed to poor road conditions, nascent infrastructural facilities, limited tradable items and lukewarm attitude of the policy-makers.

[116] There were concerns among some traders in India that Indian goods would find a limited outlet in Tibet, while China would have access to a ready market in Sikkim and West Bengal.

[117] A concern of the Indian government is also the trafficking of wildlife products such as tiger and leopard skins and bones, bear gall bladders, otter pelts, and shahtoosh wool into India.

[119] On the Indian side, only citizens of India can visit the pass on Thursdays to Sundays, after obtaining permits one day in advance in Gangtok.

While the volume of mail is declining due the advent of email and internet, it is mostly from the Tibetan Refugees in India or among the locals with relatives on both sides of the border.

This arrangement reduces the mail delivery time for the people of border areas to few days which would otherwise takes weeks to be delivered via the circuitous logistics chain.

[138] India has been planning an extension of rail services from Sevoke in West Bengal's Darjeeling district to Sikkim's capital Gangtok, 38 miles (61 km) from Nathu La.

[140] However, so far, the actual broad gauge line construction has been limited to a 45 km extension from Sevoke to Rangpo, due for completion in 2022.