the region call it ma-tho hlo/na tho lo; which may have possibly evolved to the present usage of the word. Geography Nathu La is a mountain pass on the Dongkya Range that separates Sikkim and the Chumbi Valley at an elevation of . The pass is east of Gangtok, the capital of Sikkim, and from Yatung Shasima, the headquarters of the Yadong County (or the Chumbi Valley). Nathu La is one of the three frequently-used passes between Sikkim and the Chumbi Valley, the other two being Cho La and Jelep La. Historically, Nathu La served Gangtok, while Cho La served the former Sikkim capital Tumlong and Jelep La served Kalimpong in West Bengal. Nathu La is mere northwest of Jelep La, as the crow flies, but the travel distance could be as much as . On the Tibetan side, the Chola route led to Chumbi, the Nathu La route led to a village called Chema and the Jelep La route led to Rinchengang, all in the lower Chumbi Valley. Even today, heavy snowfall causes the closure of the pass, with temperatures as low as and strong winds. History The Nathu La and Jelep La passes were part of the trade routes of the British Empire during the 19th and early 20th century. British Empire The British Raj brought the Kingdom of Sikkim under their protectorate in 1861 and wished to promote trade with Tibet through Sikkim. In 1873, J. W. Edgar, the Deputy Commissioner at Darjeeling, was asked to investigate the trading conditions and make recommendations for a preferred route. Edgar reported active trade running through the Nathu La pass ("Gnatui pass" in his terminology), which was linked to Gangtok as well as Darjeeling. The traders found significantly higher value for their goods at Darjeeling than at Gangtok. However, Edgar preferred the neighbouring Jelep La pass on physical grounds, and recommended building a road to that pass along with a trade mart close to it. Edgar wrote, In 1903-1904 Francis Younghusband led a British military expedition into Lhasa consisting of 1,150 soldiers and over 10,000 support staff and pack animals. The first choice of crossing into the Chumbi Valley had been a pass north of Nathu La, the Yak La. Yak La provided the shortest route from Gangtok to Sikkim's eastern frontier, however the eastern descent proved too steep and dangerous. Both Nathu La and Jelep La were used by