Sino-Nepal Boundary Agreement, Treaty & Protocolनेपाल–चीन सीमा सन्धि

Between 1959 and 1962, as the Sino-Indian frontier slid toward war, Nepal and China settled essentially the same kind of high-Himalayan boundary by negotiation in under three years. The method mattered: by agreeing first on principles (the 1960 Agreement), then delimiting by treaty (1961), then demarcating by protocol (1963), the two sides separated political questions from technical ones. Disputed pockets totalled only on the order of 200 square miles across as many as twenty sectors — the most serious at Rasuwa, Kimathanka, Nara Pass, Tingribode near Mustang, Mount Everest and the Nelu River — and the US State Department's boundary study notes most were settled in Nepal's favour. Beijing's flexibility, as with Burma, was strategic generosity: a demonstration aimed at Delhi and the non-aligned world that China could be a reasonable boundary partner.

Everest was the emotional core. When word spread in 1959–60 that China considered Chomolungma Chinese — Chinese maps showed it so, and no Chinese climber had yet summited — Nepali students marched in Kathmandu, and B.P. Koirala raised the matter directly with Mao Zedong, who on 18 March 1960 proposed splitting the mountain: 'Half for each side… Will that be all right?', even suggesting a boundary marker on the summit. Nepal refused any formula implying shared ownership of the summit as a single point; the eventual settlement ran the boundary along the ridge through the summit, giving each side its face of the mountain — the southern in Nepal, the northern in China. China's May 1960 first ascent from the north ridge, weeks after Zhou's Kathmandu visit, underlined what was at stake. The two countries have since cooperated on the mountain, jointly announcing its remeasured height of 8,848.86 m in December 2020.

The Joint Boundary Commission met in four sessions before the treaty — Kathmandu (August–October 1960), Peking (January–February 1961), Kathmandu (July–August 1961), Peking (October 1961) — and two more after. The boundary runs roughly 670 miles (about 1,080 km) along the Himalayan crest and is the highest international boundary on Earth, crossing Everest and Makalu. Minor issues such as pillar maintenance and the Lapcha-Limi sector persist, but the boundary is regarded as settled. For Nepal the 1961 treaty carries an extra layer of domestic meaning: it was signed at head-of-state level by King Mahendra months after his coup against the elected government whose prime minister had negotiated the 1960 agreement — proof, in palace historiography, that the monarchy could deliver national achievements; proof, in democratic historiography, that the king harvested B.P. Koirala's diplomacy.