Denisovan jawbone found in Tibet

In 1980, a Buddhist monk uncovered a mandible in Baishiya Karst Cave, more than 3,050 meters (10,000 feet) above sea level on the Tibetan Plateau. The specimen has been dated to 160,000 years ago, and analysis of proteins from its teeth indicates that it belonged to a Denisovan.[Source: Lydia Pyne, Archaeology magazine, January-February 2020]

Denisovans are an extinct group of hominins who coexisted with the Neanderthals and modern humans around 30,000 to 50,000 years ago and originated at least 200,000 years ago. Not much is known about them other than what can be gleaned from their DNA and a few rare fossils. Scientists first learned of their existence from an incomplete finger bone and two molars discovered in the Denisova Cave in the the Altai region — where Kazakhstan, Mongolia, China and Russia all come together. The finger bone and two molars have been dated by some to 80,000 years ago, but are generally placed in the 30,000 to 50,000 year old range. Denisovans disappeared about 50,000 years ago, but their DNA can be found in the genes of modern humans across Russia, east Asia, and some Pacific islands. Up to five percent of modern Papua New Guinea residents' DNA shows remnants of interbreeding with Denisovans.

Initially, scientists couldn't detect any DNA in the jawbone fossil, and without genetic proof, there was no way to be sure who the bone came from. But in February 2020, researchers returned to Baishiya Karst and were finally able to collect ancient DNA — not from bones, but from the cave floor itself. Their findings, published in the journal Science, showed that the jawbone did indeed come from a Denisovan. [Source: Aylin Woodward, Business Insider, December 9, 2020]

Implications of Denisovans in Tibet

Baishiya Karst Cave

Before the discovery in Tibet, Denisovans were previously known only through fragmentary remains of several individuals, all of which were found in southern Siberia’s Denisova Cave, which is just 700 meters (2,300 feet) above sea level and almost 2,815 kilometers (1,750 miles) northwest of Baishiya Karst Cave. “This mandible reveals that Denisovans were geographically distributed much more widely and at higher altitude than we previously thought,” says archaeologist Dongju Zhang of Lanzhou University.

Hannah Devlin wrote in The Guardian: The fossil, comprising a powerful jaw and unusually large teeth, suggests these early relatives would have looked something like the most primitive of the Neanderthals. It represents a crucial link between the Siberian specimens and other Chinese fossils, from which scientists had previously failed to extract DNA, but which show remarkable anatomical similarities to the Tibetan specimen. he scientists were not able to obtain DNA from the sample, but managed to extract proteins from one of the molars. Proteins, like DNA, could be sequenced and the analysis placed the fossil firmly on the Denisovan branch of the evolutionary tree. The paper, published in Nature, is one of the first to use protein analysis to determine an ancient human species and the technique is seen as hugely promising because protein tends to be preserved better than DNA. The team said they were hopeful that further fossils in China would be able to be tested using the method. [Source: Hannah Devlin, The Guardian, May 1, 2019]

“Kira Westaway, an archaeologist from Macquarie University in Australia who was not involved in the study, told Business Insider that the discovery put "a lot more 'meat' on the bones of the Denisovan story. It sheds light on "the nature and length of their occupation, their ability to adapt to high-altitude locations, their behavior and survival capabilities in the hostile environments of the Tibetan plateau."

Baishiya Karst Cave

The opening of Baishiya Karst Cave is about five meters (16 feet) high and seven meters (23 feet wide). When researchers dug into the frozen ground of the cave in February 2020, they found remains of gazelles, foxes, and rhinos along with stone tools. They also extracted DNA from different layers of cave sediment that dated back 100,000, 60,000, and 45,000 years. “Similar to a CSI crime scene, human DNA from blood, sweat, and skin cells can be found everywhere that humans occupy. And the freezing-cold climate of the Tibetan plateau is the perfect environment for DNA preservation," Westaway said.

“Genetic analysis revealed that the DNA was Denisovan, since it matched genetic markers from the bones found in Denisova cave. That confirmed that the jawbone discovered in 1980 was "the first skeletal evidence of Denisovans outside of Denisova cave," Westaway said. Anthropologists determined in 2019 that the jawbone was 160,000 years old. That finding, coupled with the more recent finding of 45,000-year-old cave sediment with DNA in it, suggests Denisovans consistently occupied Baishiya Karst cave for more than 100,000 years.

According to Business Insider: “Denisovans, it seems, lived on this part of the Tibetan Plateau at least 120,000 years before modern humans showed up. They were able to survive at altitudes of more than 10,000 feet. Temperatures on the plateau during the time they were there could have hit a bone-chilling negative 22 degrees Fahrenheit.

Did Denisovan DNA Helped Tibetans Live at High Altitudes

origin and dispersal of Denisovan DNA

According to Archaeology magazine: Studies of Denisovan genetic material had detected a mutation that fosters survival in low-oxygen environments found in extremely high-altitude locations such as the Tibetan Plateau. This same mutation has been identified in present-day Tibetans, and the discovery that Denisovans once inhabited the region may explain how they obtained this life-preserving adaptation. [Source: Lydia Pyne, Archaeology magazine, January-February 2020]

Business Insider reported: “Usually, when humans reach high altitudes (where oxygen levels are lower), our bodies make more hemoglobin, the protein in red blood cells that helps carry oxygen from the lungs to the rest of the body. But too much hemoglobin can make it harder for the heart to pump blood around. That can lead to mountain sickness and heart attacks. Many Tibetans don't experience this issue, however, because their bodies don't make that extra hemoglobin. Instead, their DNA contains a gene called EPAS1, which prevents that blood-thickening process. That gene comes from Denisovans. The idea that modern Tibetans' owe their unique adaptation to oxygen-scarce environments to ancient human interbreeding with Denisovans was first introduced in a 2014 study. The discovery of the Denisovan jawbone and DNA in Tibet adds credence to that line of thinking.

The cave in which the fossil was found is in a rugged valley on the mountainous Tibetan plateau. Hannah Devlin wrote in The Guardian:“The discovery indicates that Denisovans adapted to high-altitude, low-oxygen environments much earlier than the regional arrival of modern humans about 40,000 years ago. It also helps explain how present-day Sherpas and some Tibetan populations came to carry a gene of Denisovan origin — presumably acquired through ancient interbreeding — that allows these populations to cope with hypoxia. “This has been quite puzzling because the [Siberian] cave was not at high altitude,” said Hublin. [Source: Hannah Devlin, The Guardian, May 1, 2019]

Previously scientists had assumed the gene most probably served a different purpose in Denisovans, such as helping them cope with intense physical activity, and that it was later coopted for a different purpose. Stringer said: “Now it seems more likely that it originated in high altitude-adapted Denisovans, and could have been passed on directly in the region.” Scientists could not be certain of this, though, because they were unable to extract a genome from the new specimen.

Jean-Jacques Hublin, the director of the department of human evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig and senior author of the find, described this element as “spectacular”. He said: “Until today, nobody imagined that archaic humans could be able to dwell in such an environment. The dating of the mandible suggests temperatures on the plateau would have been even harsher than today, when temperatures can plunge to -30C (-22F). “It’s a time period colder than now which … blows my mind. If you find it a challenging environment today, I recommend you try it [then].”

200,000-Year-Old Handprints from Tibet — the World’s Earliest Cave Art?

Fossilized children's handprints and footprints found near a hot spring in Tibet could be 200,000 years old, according to one study, making them the oldest cave art ever found. The prints were made in travertine stone which is soft when it's wet and hardens when it dries. There is a debate among archaeologists as to whether the handprints are really art and whether they are as old as claimed. A study on the prints was published September 2021 in the journal Science Bulletin. “The question is: What does this mean? How do we interpret these prints? They’re clearly not accidentally placed,” study co-author Thomas Urban, a scientist at Cornell University’s Tree-Ring Laboratory, said. [Source: Tom Metcalfe, Live Science, February 3, 2024; Isis Davis-Marks, Smithsonian magazine, September 17, 2021

200,000 year old Tibetan hand and foot prints

Isis Davis-Marks wrote in Smithsonian magazine: Between 169,000 and 226,000 years ago, two children in what is now Quesang, Tibet, left a set of handprints and footprints on a travertine boulder. Seemingly placed intentionally, the now-fossilized impressions may be the world’s oldest known parietal, or cave, art. The prints were dated using the uranium series method. The ten impressions—five handprints and five footprints—are three to four times older than comparable cave paintings in Indonesia, France and Spain. Given their size and estimated age, the impressions were probably left by members by the genus Homo. The individuals may have been Neanderthals or Denisovans rather than Homo sapiens.

The discovery offers the earliest evidence of hominins’ presence on the Tibetan Plateau and supports previous research indicating that children were some of the first artists. Researchers discovered the hand and footprints — believed to belong to a 12-year-old and 7-year-old — near the Quesang Hot Spring in 2018. Though parietal art typically appears on cave walls, examples have also been found on the ground of caverns. “How footprints are made during normal activity such as walking, running, jumping is well understood, including things like slippage,” Urban told “These prints, however, are more carefully made and have a specific arrangement—think more along the lines [of] how a child presses their handprint into fresh cement.”

Do the Tibetan prints constitute art? Matthew Bennett, a geologist at Bournemouth University who specializes in ancient footprints and trackways, told Gizmodo that the impressions’ placement appears intentional: “It the composition, which is deliberate, the fact the traces were not made by normal locomotion, and the care taken so that one trace does not overlap the next, all of which shows deliberate care.” Other experts don’t necessarily buy into this. “I find it difficult to think that there is an ‘intentionality’ in this design,” Eduardo Mayoral, a paleontologist at the University of Huelva in Spain told NBC News.“And I don’t think there are scientific criteria to prove it—it is a question of faith, and of wanting to see things in one way or another.”

Evidence of People Living in Tibet Continuously Since 62,000 Years Ago

In a study published in September 2016 in the American Journal of Human Genetics researchers sequenced the entire genomes of 38 ethnic Tibetans and 39 Han Chinese and compared the results with published genomic sequences of other ethnic groups around the world, which allowed the scientists to isolate the common genetic origin of different populations and get an idea of how people migrated to and lived in Tibet. “Tibetan-specific DNA sequences can be traced back to ancestors 62,000-38,000 years ago…This represents the earliest colonization of the Tibetan Plateau,” says Shuhua Xu, a population geneticist at the Chinese Institute of Sciences’ Shanghai Institutes for Biological Sciences, who authored the study. [Source: Scientific American, December 28, 2016]

Scientific American reported: “Since that initial migration, as the ice age tightened its grip on the plateau, genetic mixing between Tibetans and non-Tibetans probably ground to a halt for tens of thousands of years—suggesting that movement into Tibet dropped to the minimum. “The migration routes were probably cut off by ice sheets,” Xu says. “It’s simply too harsh even for the toughest hunter-gatherers.” But about 15,000 to 9,000 years ago—after the so-called last glacial maximum (LGM), during which the Earth’s ice cover had reached its most extensive point and climate was at its harshest—people flocked into Tibet en masse. “It’s the most significant wave of migration that shaped the modern Tibetan gene pool,” Xu says. “We can really see rapid population expansion [on the plateau] during that time.” Interestingly, he adds, this was also when the common ancestor of Tibetans and Han Chinese split—contrary to a previous study suggesting that the divergence took place as late as 2,750 years ago.

Migration routes to the Tibetan plateau, there may be others

“The study, Mark Aldenderfer, an archaeologist at the University of California, Merced, who was not involved in Xu’s study, says “also provides fine details of how different populations from various directions may have combined their genes to ultimately create the people that we call Tibetans.” The data show that 94 percent of the present-day Tibetan genetic makeup came from modern humans—possibly those who ventured into Tibet in the second wave of migration—and the rest came from archaic hominins such as Denisovans, Neandertals and unknown groups. The modern part of the Tibetan genome shares 82 percent similarity with East Asians, 11 percent with Central Asians, and 6 percent with South Asians. “Among all ethic groups, Han Chinese are most closely related to Tibetans,” Xu says.

“The findings also reveal a startling genetic continuity since the plateau was first colonized 62,000 years ago. “This suggests that Tibet has always been populated—even during the toughest times as far as climate was concerned,” Xu says. That idea contradicts the commonly held notion that any early plateau dwellers would have been eliminated during harsh climate intervals such as LGM and another period known as the Younger Dryas between 12,900 and 11,600 years ago, says David Zhang, a geographer at the University of Hong Kong, who was not involved in Xu’s research.

“In 2002 Zhang and a colleague published a controversial study in Geophysical Review Letters showing marks of hands and feet from at least six individuals in rocks that were once soft mud, which was dated to 20,000 years ago at 4,000 meters above sea level in the heart of Tibet. Based on this they theorized that people were living in Tibet at the height of LGM, but the lack of archaeological finds near the site has cast doubt on this. “Many people don’t think it’s possible,” Aldenderfer says. “But there were plenty of places for [those early populations] to live where local conditions weren’t that bad, such as the big river valleys on the plateau.” The handprints and footprints were uncovered near one of the plateau’s many hot springs, which could have served as refuges for plants, animals and humans, he adds.

“Two independent archaeological studies presented at the 33rd International Geographical Congress, held in August in Beijing, also support the antiquity of Tibet settlement as suggested by Xu’s genetic data. A team led by archaeologist Guanghui Dong of Lanzhou University in Gansu province unveiled the earliest archaeological evidence of human presence—dating to 39,000-31,000 years ago—on the southeastern fringe of the Tibetan Plateau. The site, rich with stone tools and animal bones, lies at 2,500 meters above sea level at the bank of the Salween River. “This may represent one of the first steps of human colonization on the plateau,” Dong says. “Those hunter-gathers might then expand to the inner plateau along the river valley.”

Neolithic Tibet

Neolithic Age pot from Tibet

Tibet been inhabited since the Late Paleolithic era. Evidence of an intermittent human presence on the Tibetan Plateau has been dated to at least 30,000 years ago, with the first semi-permanent villages established only 5,200 years ago. Archeological evidence indicates that people arrived on the Tibetan plateau from the northeast approximately 13,000 year ago. Over time they migrated throughout the region with large numbers settling along the Tsangpo River, which runs parallel to the Himalayas in southern Tibet.

The Tibetans first settled along the middle reaches of the Yarlung Zangbo River (Brahmaputra River) in Tibet. Evidence of the new and old stone age culture was found in archaeological excavations at Nyalam, Nagqu, Nyingchi and Qamdo. According to ancient historical documents, members of the earliest clans formed tribes known as "Bos" (or “Pos”) in the Shannan area—Lhoka, located on the middle and lower reaches of the Yarlung Valley in southern Tibet near the present-day border with Bhutan. [Source: ]

According to Archaeology magazine: Due to its perennially freezing temperatures and low-oxygen conditions, human habitation of the Tibetan Plateau is exceedingly challenging. Yet, somehow, humans have lived there for 30,000 to 40,000 years, as evidenced by thousands of fragments of human-made stone tools and blades from the site of Nwya Devu. Located 15,000 feet above sea level, Nwya Devu is the highest Paleolithic site ever identified, and proves that humans were living along the “roof of the world” almost 20,000 years earlier than expected. [Source: Archaeology magazine, March-April 2019]

According to study published in 2015 at more than 50 sites across the Tibetan Plateau, barley was essential to life at high elevation. Nomadic people had traversed the region for thousands of years, and around 5,200 years ago they began to settle. But even then they did not live more than 8,000 feet above sea level. Around 3,600 years ago they moved to higher elevations, up to 11,000 feet. The researchers believe that the introduction of barley, which is frost-tolerant, was the key to living on the roof of the world. [Source: Samir S. Patel Archaeology magazine, March-April 2015]

Neolithic Migrations of People in Tibet, China, Mongolia and Central Asia

During the mid-Holocene (11.700 years ago to present), Neolithic immigrants from northern China largely replaced the original inhabitants, bringing with them elements of Neolithic culture and technology, although a degree of genetic continuity with the Paleolithic settlers still exists. The neolithic settlers from northern China were possibly from a mixture of the Yangshao culture, which inhabited modern-day Henan, Shaanxi, and Shanxi, and the Majiayao culture, which inhabited the upper Yellow River region in modern-day Gansu and Qinghai. [Source: Wikipedia]

Archaeological evidence suggests that the spread of the Sino-Tibetan proto-language was caused by the westward expansion of the Yangshao culture, intermingling with the Majiayao culture, which expanded further west into the Himalayas.

The neolithic cultures of Kashmir, northern Sikkim, Chamdo, and Bhutan are all the result of this migration into the Tibetan Plateau, primarily through the use of two routes: 1) the southward route through modern-day Sichuan into Sikkim, Bhutan and southeastern Tibet, and 2) a westward path through the Karakoram mountain range, into Kashmir. The divergence in the Sino-Tibetan language family between the Bodish languages, including the Tibetan languages, and the Sinitic languages of China likely occurred during this migration. [Source: Wikipedia +]

Evidence of neolithic Tibetan inhabitants and settlements have been found mainly "in river valleys in the south and east of the country". Archaeological sites consist of those in Nyingchi County, Medog County, and Qamdo County. Archaeologists have found pottery and stone tools, including stone axes, chisels, knives, spindle-whorls, discs, and arrowheads. Findings in Nyingchi culturally resemble the Neolithic Qijia culture in Gansu and Qinghai, while findings in Qamdo resemble the Dadunzi site in Yunnan, although there may be some connections with the Neolithic culture of the Yellow River valley. +

According to Namkhai Norbu some Tibetan historical texts identify the Zhang Zhung culture as a people who migrated from the Amdo region into what is now the region of Guge in western Tibet. Zhang Zhung is considered to be the original home of the Bön religion. By the 1st century B.C., a neighboring kingdom arose in the Yarlung Valley, and the Yarlung king, Drigum Tsenpo, attempted to remove the influence of the Zhang Zhung by expelling the Zhang's Bön priests from Yarlung. He was assassinated and Zhang Zhung continued its dominance of the region until it was annexed by Songtsen Gampo in the 7th century. +

DNA Evidence of People Living in Tibet 30,000 Years Ago

According to the abstract of “Genetic evidence of Paleolithic colonization and Neolithic expansion of modern humans on the Tibetan Plateau” published Molecular Biology and Evolution in May 2013: “The Tibetan Plateau is a remarkable area for cultural and biological studies of human population history. However, the chronological profile of the Tibetan Plateau's colonization remains an unsolved question of human prehistory. [Source: “Genetic evidence of Paleolithic colonization and Neolithic expansion of modern humans on the Tibetan Plateau” by Xuebin Qi, Chaoying Cui, Yi Peng, Xiaoming Zhang, Zhaohui Yang, Hua Zhong, Hui Zhang, Kun Xiang, Xiangyu Cao, Yi Wang, Ouzhuluobu, Basang, Ciwangsangbu, Bianba, Gonggalanzi, Tianyi Wu, Hua Chen, Hong Shi, and Bing Su, Molecular Biology and Evolution, May 12, 2013 |:|]

“To reconstruct the prehistoric colonization and demographic history of modern humans on the Tibetan Plateau, we systematically sampled 6,109 Tibetan individuals from 41 geographic populations across the entire region of the Tibetan Plateau and analyzed the phylogeographic patterns of both paternal (n = 2,354) and maternal (n = 6,109) lineages as well as genome-wide SNP markers (n = 50) in Tibetan populations. We found that there have been two distinct, major prehistoric migrations of modern humans into the Tibetan Plateau. The first migration was marked by ancient Tibetan genetic signatures dated to around 30,000 years ago, indicating that the initial peopling of the Tibetan Plateau by modern humans occurred during the Upper Paleolithic rather than Neolithic. |:|

” We also found evidences for relatively young (only 7-10 thousand years old) shared Y chromosome and mitochondrial DNA haplotypes between Tibetans and Han Chinese, suggesting a second wave of migration during the early Neolithic. Collectively, the genetic data indicate that Tibetans have been adapted to a high altitude environment since initial colonization of the Tibetan Plateau in the early Upper Paleolithic, before the Last Glacial Maximum, followed by a rapid population expansion that coincided with the establishment of farming and yak pastoralism on the Plateau in the early Neolithic.” |:|

Neolithic Sites Found Near 5,000 Meters in Tibet

In 2003, archeologists announced they had discovered several sites used by Neolithic people in Tibet at almost 5,000 meters above the sea level. The 13 prehistoric sites, located on the Tanggula Range on the Qinghai -Tibet Plateau, were discovered during the exploration of the Tibetan section of the Qinghai-Tibet railway. [Source: Xinhua News Agency November 5, 2003]

Xinhua reported: “Distributed on the Tanggula Range, the sites were all at an altitude of between 4,700 and 4,900 meters above sea level, said Gengdui, a research fellow with the Tibet Museum. "From those sites of 4,900 meters high, we can draw the conclusion that ancient people living on the Qinghai-Tibet Plateau could move about in an area above 5,000 meters," said he. "Located along the banks of the Buqu River snaking in the Tanggula Range, most of the sites are shelters from the wind, close to water and convenient for communications, thus providing suitable living conditions," he said.

Some of the instruments discovered at the sites are made of quality stone and of a high degree of technical skill. "Most of the instruments have multiple uses, a main characteristic of instruments unearthed in the prehistoric cultural sites in the Eurasia Continent," he said. "Such instruments have also been discovered at other places in Tibet. So we consider it forceful evidence for the existence of ancient humans on the Qinghai-Tibet Plateau," he added.

Prehistoric Farming on the Tibetan Plateau

In November 2014, archaeologists announced they had found evidence of 3,600-year-old crop growing and the raising of livestock taking place year-round at very high altitudes on the Tibetan Plateau. Cambridge University reported: “Animal teeth, bones and plant remains have helped researchers from Cambridge, China and America to pinpoint a date for what could be the earliest sustained human habitation at high altitude. The findings, published today in Science, demonstrate that across 53 archaeological sites spanning 800 miles, there is evidence of sustained farming and human habitation between 2,500 meters above sea level (8,200ft) and 3,400 meters (11,154ft). [Source: University of Cambridge press release, November 21, 2014 +++]

“The presence of crops and livestock at the altitudes discovered by researchers indicates a more sustained human presence than is needed to merely hunt game at such heights. Professor Martin Jones, from Cambridge’s Department of Archaeology, and one of the lead researchers on the project, said: “Until now, when and how humans started to live and farm at such extraordinary heights has remained an open question. Our understanding of sustained habitation above 2-3,000m on the Tibetan Plateau has to date been hampered by the scarcity of archaeological data available. But our findings show that not only did these farmer-herders conquer unheard of heights in terms of raising livestock and growing crops like barley and millet, but that human expansion into the higher, colder altitudes took place as the continental temperatures were becoming colder. Year-round survival at these altitudes must have led to some very challenging conditions indeed – and this poses further, interesting questions for researchers about the adaptation of humans, livestock and crops to life at such dizzying heights.” +++

“The research “raised interesting questions about the timing and introduction of Western crops such as barley and wheat – staples of the so-called ‘Fertile Crescent’. From 4,000-3,600 years ago, this meeting of east and west led to the joining or displacement of traditional North Chinese crops of broomcorn and foxtail millet. The importation of Western cereals enabled human communities to adapt to the harsher conditions of higher altitudes in the Plateau. +++

“In order to ascertain during what period and at what altitude sustained food produced first enabled an enduring human presence, the research group collected artefacts, animal bones and plant remains from 53 sites across the late Yangshao, Majiayao, Qiija, Xindian, Kayue and Nuomuhong cultures. Cereal grains (foxtail millet, broomcorn millet, barley and wheat) were identified at all 53 sites and animal bones and teeth (from sheep, cattle and pig) were discovered at ten sites. Of the 53 sites, an earlier group (dating from 5,200-3,600 years ago) reached a maximum elevation of 2,527m while a later group of 29 sites (dating from 3,600-2,300 years ago) approached 3,400m in altitude. +++

“Professor Jones believes the Tibetan Plateau research could have wider and further-reaching implications for today’s world in terms of global food security and the possibilities of rebalancing the ‘global diet’; at present heavily, and perhaps unsustainably, swayed in favour of the big three crops of rice, wheat and maize. He said: “Our current knowledge of agricultural foods emphasises a relatively small number of crops growing in the intensively managed lowlands. The more we learn about the rich ecology of past and present societies, and the wider range of crops they raised in the world’s more challenging environments, the more options we will have for thinking through food security issues in the future.” +++

Image Sources: Wikimedia Commons, Purdue University, University of Washington

Text Sources: 1) "Encyclopedia of World Cultures: Russia and Eurasia/ China", edited by Paul Friedrich and Norma Diamond (C.K.Hall & Company, 1994); 2) Liu Jun, Museum of Nationalities, Central University for Nationalities, Science of China, China virtual museums, Computer Network Information Center of Chinese Academy of Sciences, ~; 3) Ethnic China *\; 4); 5), the Chinese government news site | New York Times, Washington Post, Los Angeles Times, Times of London, Lonely Planet Guides, Library of Congress, Chinese government, The Guardian, National Geographic, Smithsonian magazine, The New Yorker, Time, AP, AFP, Wikipedia, BBC, and various books, websites and other publications.

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