Hoh Xil

Hoh Xil is a massive, isolated region located in the northeastern part of the Qinghai-Tibet Plateau. It is known by several names. In Mongolian, the name means "Blue Ridge." Another name, Aqênganggyai, means "Lord of Ten Thousand Mountains."

This region is globally significant for its extreme scale. On July 7, 2017, UNESCO listed the area as a World Heritage Site. It is described as the largest and highest plateau in the world. This status recognizes its unique geography and importance.

The geography of Hoh Xil is defined by its immense size and high altitude. The region covers 83,000 square kilometres of land. It stretches east to west between two major mountain chains. These are the Tanggula and Kunlun mountains. The area sits across the borders of several Chinese regions. It includes parts of the Tibet Autonomous Region, Qinghai Province, and the Xinjiang Uyghur Autonomous Region. Most of the land sits at an average elevation of 4,800 metres above sea level.

Water moves through this high landscape in two distinct ways. In the southeastern part of the region, the Chumar River flows through the land. This river serves as one of the major headwater sources for the Yangtze River. However, the rest of the region is endorheic. This is a term hydrologists use for drainage systems that do not reach the ocean. Instead, the water flows into many isolated lakes. Because of these many lakes, scientists often call this area the "Hoh Xil lake district."

The geological foundation of Hoh Xil is volcanic in nature. It is part of the Northern Tibet volcanic field. This field contains many volcanoes from the late-Cenozoic era. Some of these are Hawaiian-style volcanoes. One specific area is Bamaoqiongzong, which covers 300 square kilometres. It features a perfectly preserved edifice to the northeast of its summit. The rocks there include peralkaline phonolitic and foiditic types. Another site, Yongbohu, contains five different vents. These vents are made of dacitic, trachyandesitic, and andesitic rock.

Conservation efforts have focused on protecting this fragile environment for decades. In 1995, a large portion of the region became a national nature reserve. This reserve covers 45,000 square kilometres. The average elevation in this protected area is 4,600 metres. The UNESCO World Heritage Site includes the western half of Zhidoi County. It also includes the western part of Qumarlêb County in Qinghai. Bukadaban Feng is also considered part of the Hoh Xil region.

Despite the harsh climate, Hoh Xil supports a diverse range of wildlife. There are more than 230 species of wild animals living here. Twenty of these species are under Chinese state protection. You can find wild yaks, wild donkeys, and white-lip deer in the area. The region is also home to brown bears. These bears eat plateau pikas, which are small burrowing rodents. They also eat yak and antelope. The Tibetan antelope, also called the chiru, is an endangered species. Many of these animals gather at Zhuonai Lake.

The 2004 film *Kekexili: Mountain Patrol* helped make the chiru and this region famous in China.

Modern transportation allows people to travel near the edges of this massive plateau. The Qingzang Railway and China National Highway 109 run along the eastern boundary of the reserve. Engineers have built impressive structures to navigate the high altitude. One such structure is the Fenghuoshan Tunnel. This is currently the highest railway tunnel in the world. The tunnel is 1,338 metres long. Its entrances are located at an elevation of 4,905 metres above sea level. These connections link the remote plateau to the rest of the country.