An introduction to the geography of the Eastern Nyanchen Tanglha (Nyainqentanglha) and a journey from the waters of the Yi’ong Tso to the primarily Bomi village of Bake along the lower Yi’ong Tsangpo. The “Alps of Tibet” east of the Himalaya spread from the Qinghai-Tibetan Plateau to the western rim of the Sichuan basin. The upper streams of Asia’s five great rivers flow north to south, forming deep valleys. At one point these five rivers are squeezed into a span of just 150km before continuing their journey farther south. The Yangtze enters the Pacific near Shanghai, the Mekong enters the South China Sea, the Salween and Irrawaddy flow into the Andaman Sea and Rohit, and finally the principal river, the Tsangpo-Brahmaputra, flows into the Bay of Bengal (Indian Ocean).
The Nyanchen Tanglha East is located on the southeastern rim of the Qinghai-Tibetan Plateau and forms the watershed between the Yarlung Tsangpo and Salween River (Nu Jiang). To the north this is the Upper Salween, while to the south lie the two tributaries of the Yarlung Tsangpo: Yi’ong Tsangpo and Parlung Tsangpo. Numerous peaks have never been seen, let alone visited. The rivers erode the plateau into deeply carved valleys, and the topography is complicated. The highest peak in the main range is Sepu Kangri (6,956m), climbed by an American party in 2002.
The Po Tsangpo, a tributary of the Yarlung Tsangpo north of the Tsangpo Gorge, separates into the Yi’ong Tsangpo and Parlung Tsangpo at the confluence near Tongmai. The Yi’ong Tsangpo flows from west-northwest almost due east, then turns gradually southwards in the middle of Lake Yi’ong. The distance from the source to confluence is about 230km as the crow flies but the total river length is 286km, as it zigzags through deep gorges. We tentatively define the section (125km as the crow flies) from the source to Niwu (Nye) as the upper part, which belongs to Lhari County, and the section (105km) from Niwu to the confluence with the Po Tsangpo as the lower part, which belongs to Bomi County.
To the north and northeast of the lower Yi’ong Tsangpo lie the largest glaciers in East Tibet, such as Qiaqing (35km) and Jiangpu (21km), with stunning unclimbed 6,000m peaks soaring at their heads. Although there are no large glaciers to the south of the river, there are still challenging peaks of 5,600-6,300m.
A vehicle road has been constructed from Lhari to Niwu along the upper Yi’ong Tsangpo, but it is dangerous and vulnerable to landslides, which sometimes block traffic. The lower part, which flows through deep gorges, has no vehicle road, only a mule track along the right bank. However, it is not possible to follow even the mule road in its entirety with animals. Horses are unable to negotiate a section near Niwu, where to avoid a terrifically deep gorge, the route becomes a narrow trail clinging to precipitous slopes. The humid climate brings much snowfall, which feeds glaciers, forms impressive snow peaks, and grows beautiful conifer forests. Both sides of the Yi’ong Tsangpo resemble dense subtropical rainforest.
Bailey and Morshead reached Lake Yi’ong in 1913 and discovered it had only been formed 12 years earlier (see Baileys No Passport to Tibet). In 1935 Kingdon-Ward traveled up the Yi’ong Tsangpo and was the first foreigner to complete the entire track from Lake Yi’ong to Niwu (Kingdon-Ward, Assam Adventure). In November 2005 Tsuyoshi Nagai (73) and I (70) became the first foreigners to repeat this journey, on my fourth attempt since 2001.1 found Tangmai to be a hive of new construction, compared with my first visit in 1999, when it was a deserted village with a couple of shabby houses. We reached the Yi’ong Tso (lake) by Land Cruiser and then trekked northwest towards the Daoge Glacier, but were unable to see it due to poor weather. We returned and trekked up the lower Yi’ong Tsangpo to the village of Bake, where we were told we were the first foreigners ever to visit. A more detailed account appears in the 2006 Japanese Alpine News, Vol. 7
Tamotsu Nakamura, Japan