The main yak caravan between Tibet's capital Lhasa and Chamdo, the second city in the northeast corner, runs across passes south of the icy range of Nyangla Tang Shan, crossing it by a pass to the east of the Sepu Kangri massif, in Diru County. Traders from time immemorial have used this route, ferrying salt to Chamdo and bringing back timber from the lush forest s of eastern Tibet to the barren Lhasa valley. Glimpses of high peaks, eighty kilometers away, slip through the clouds. But nowhere in the written accounts of Tibetan journeys can we find any record of Sepu Kangri, the Great Snow Peak above the Holy Lake.

As westerners keen to be the first into remote corners of the globe, it is easy for us to claim the first view of this great mountain. Clearly, when the six members of the British Everest Expedition in 1982 looked out of an aircraft window and saw a vast range of unknown mountains to the north, we claimed them as our own. But someone else, monk, nomad or trader knew of Sepu Kangri many years before, and perhaps admired it's icy towers and forbidding glaciers.

Central Tibet has had a few European explorers, and no one in the 19th century penetrated deep into Diru County, at the headwaters of the Salween. This great river whose source is in these mountains, ends on the coast of Burma three thousand miles later, pouring foetid muddy water into the bay of Bengal.

One remarkable expedition, a two man team of botanists, walked from Burma in 1935 to try to reach the source of the Salween, high in the Tibetan plateau, about 100km from Naqchu, then a small town four days journey from Lhasa and now a booming industrial centre. Ronald Kaulbeck and John Hanbury-Tracy walked nearly three thousand miles in twenty-two months, approaching Diru County from the south east. A political disoute halted their progress in December 1935, at the Diru County headquarters. They were allowed no further. Their book 'Salween' tells of the story, but nowhere within it is there a mention of this great hidden range which they passed close by. As we were to discover, Sepu Kangri remains a hidden peak until you are standing underneath it.