Initial survey Mount Gipmochi received a prominent position in British geography of the region because it is one of the peaks visible from
Darjeeling, which the British leased from the
Chogyal of Sikkim in 1835 in return for an annual subsidy. They had free access to the tract around Darjeeling, but not to Sikkim proper. Numerous Himalayan peaks were however visible from Darjeeling. Surveyor Reginald Walker, who was in charge of the Eastern Himalayan survey in 1847, suggested that a suitable base line at sufficient distance can be used to measure the locations and heights of the high Himalayan peaks. After Walker's premature death,
Andrew Scott Waugh, the
Surveyor General of India, joined the Darjeeling survey party and fixed the positions and heights of all the visible peaks using trigonometric methods. Despite the great distance from which the peaks were measured, the positions were said to be correct to within quarter of a second in latitude and half a second in longitude.
Misplacement of Gipmochi (1854); marked on the far right is "Gipmochi of Col. Waugh, 14,509". Mount Gipmochi started appearing British maps around 1850 in the process of illustrating the travels of the noted British botanist
Joseph Dalton Hooker. Hooker toured the then independent state of Sikkim to explore and collect samples of Himalayan plants. After touring the northern Sikkim (
Lachung area), he returned to the then Sikkimese capital
Tumlong, and along with
Archibald Campbell, the superintendent of Darjeeling, attempted to go to
Chumbi via the
Cho La pass. The Sikkimese authorities prohibited them from entering Tibetan territory, and arrested them near the pass. Evidently, Mount Gipmochi was visible from their route, and Hooker remarked that the Dongkya Range gradually sinks into Bhutan near Gipmochi. Hooker placed Gipmochi directly on the Dongkya range, and attributed its position to Waugh. For several decades after this, the Mount Gipmochi continued to be shown on the Dongkya range despite other evidence to the contrary. After the Hooker episode, the British signed the
Treaty of Tumlong (1861) with Sikkim, bringing the state under their
protectorate. All the previous restrictions on travel in Sikkim were removed. In 1864, the
Anglo-Bhutan War was fought, at the end of which, through the
Treaty of Sinchula, the British gained control over the present day
Kalimpong district. This paved the way for a direct trade routue from Darjeeling to the Sikkim passes.
Richard Temple, the lieutenant-governor of the
Bengal Presidency during 1874–1877, states that the British had begun to construct a cart road to the
Jelep La pass for trade with Tibet. Temple explored the lake region of Sikkim and presented his findings at the
Royal Geographical Society in 1881. One of his sketches showed
Bitang Tso (or Kupup Lake) viewed from
Kupup in Sikkim, with Mount Gipmochi in the background. His cartographer however continued to show Mount Gipmochi on the Dongkya range, in the tradition of Joseph Hooker, and placed the Bitang Tso to its south in Bhutanese territory. (Map 3) Temple himself invoked the authority of Hooker, stating, "In Sir Joseph Hooker's 'Himalayan Journals' the name Gipmochi is always applied to the mountain which terminates the Chola range [Dongkya range]."
Convention of Calcutta 20th century The Imperial Gazetteer of India states that the Dongkya range (or Chola range) that divides
Sikkim from the
Chumbi Valley bifurcates at Gipmochi into two great spurs, one running to the south-east and the other to the south-west. Between the two spurs lies the valley of the Dichul (
Jaldhaka) river. The "western shoulder" of Gipmochi was said to contain the trijunction point of Sikkim, Bhutan and Tibet. The southwest spur mentioned in the Gazetteer forms part of the boundary between Sikkim and Bhutan. The southeast spur, called the
Zompelri ridge (or
Jampheri ridge), currently separates the Bhutanese districts of
Haa (to the north) and
Samtse (to the south). The area bounded by Gipmochi and Batang La, extending about 5 km to the southeast, forms a plateau called
Dolam or
Doklam plateau. Some British travel maps from the 19th century (prior to official surveys) mark this plateau as "Gipmochi Pk" and show its alignment with the Sinchela pass (on the northern ridge of the plateau). Bhutan did not have a map of its lands till 1961. == Chinese border claims ==