Researchers working at the Piluo site Photo: Courtesy of CHEN SHENGQIAN

Touching down at Daocheng Yading Airport from Chengdu Shuangliu was a bit rough—the plane seemed to slam down onto the runway, giving us all a jolt. Even more surprising, the sealed bags holding small bread rolls began popping open one after the other, likely due to the altitude. Yading Airport, at an altitude of 4,411 meters, is currently the highest civilian airport in the world. We were on our way to see the Piluo site in Daocheng, Sichuan, one of the most significant Paleolithic archaeological discoveries on the Qinghai-Tibet Plateau in recent years. I’ve long been curious about what drew humans to the plateau during the sparsely populated Paleolithic era. How did they adapt to such a harsh environment?

In Daocheng, I experienced firsthand the challenges of the plateau. Severe altitude sickness and acclimatization issues gave me headaches, muscle weakness, vomiting, and diarrhea, which only improved with oxygen therapy and medication. Despite these challenges, I managed to observe the entire site and the excavated specimens, deepening my understanding of the importance of the Piluo site. 

Unique significance of Piluo site

Firstly, my questions about dating have been clarified. At Piluo, a complete sequence of cultural deposits lies within a stratigraphy over two meters deep, comprising ten distinct layers. The Qinghai-Tibet Plateau is a region formed by geological uplift and denudation, where stratified deposits are rare and many previously discovered Stone Age sites are exposed, complicating dating efforts. Piluo, however, features four distinct cultural layers, which is quite rare. These four layers correspond to four periods, with the earliest representing pebble-based craftsmanship, where river pebbles were used as raw materials to produce tools such as flakes and choppers—a relatively simple craftsmanship commonly seen in southern China. The second period features Acheulean craftsmanship with hand axes, thin axes, and hand picks. The hand axes are relatively standard in form, slightly thinner than usual, and the hand picks are also somewhat smaller than commonly seen in southern China. Tools of the Acheulean type primarily spread across Africa and the western side of the Eurasian continent. In the third period, a small bifacial-tool tradition emerged, featuring notably smaller hand axes and other bifacial tools that distinguish it from the second period. The fourth period features a flake-tool tradition with quartz as the main raw material. These four periods present distinct characteristics, making them easy to differentiate. Notably, the excavators conducted systematic optically stimulated luminescence (OSL) dating of the site, establishing a complete chronological sequence. The ages of these cultural layers range from over 200,000 years ago to around 60,000 years ago. The methodical excavation, solid stratigraphic evidence, systematic dating, and complete chronological sequence make Piluo’s dating remarkably credible. 

Secondly, my doubts surrounding the hand axes at Piluo have also been dispelled. The hand axes unearthed at the site are quite standard in form, with bifacial fashioning and a processing depth that goes beyond the midline, and there is thinning along the bottom edge. In form, these hand axes closely resemble those from western Eurasia, apart from minor asymmetries. In contrast, hand axes found at other sites in China are generally less standardized, with many retaining natural pebble surfaces on the bottom edge, which has led to their classification as “pseudo-hand axes.” The Piluo hand axes are not only typical in shape but also found in significant quantities. What’s more important is the presence of thin axes and hand picks alongside the hand axes, together forming a complete Acheulean craft complex. The presence or absence of Acheulean industry has been an unresolved issue within Chinese Paleolithic archaeology for many years. Over the past several decades, regions like the Baise Basin, Luonan Basin, and Xiangfen Basin in China have revealed many stone tool assemblages similar to Acheulean tools. Yet, the presence of natural pebble edges on some hand axes distinguishes them from typical Eurasian hand axes, generating skepticism about whether a true Acheulean tradition existed in Paleolithic China. The findings at Piluo offer a convincing answer, making it untenable to claim that hand axes or Acheulean crafts were absent from China’s Paleolithic era. 

Paleolithic explorations of Qinghai-Tibet Plateau

Finally, let’s return to the initial question: why did humans venture onto the Qinghai-Tibet Plateau? The Piluo site provides an answer based on natural conditions. Located on a small hill at an altitude of 3,775 meters, Piluo is in an advantageous position with several streams converging at the mountain’s foot, offering a broad view of the entire valley. For hunter-gatherers, such a panoramic vantage point would have been crucial. The valley is the same location as the present-day county seat, chosen by people both ancient and modern for its favorable conditions. Today, Daocheng Yading is a popular tourist destination, known as “the last pure land on the blue planet.” This region is a scenic mix of plateaus, valleys, and the picturesque Shangri-La Town of Yading, which sits at an elevation of only 2,800 meters. Within the valley are forests, grasslands, farmland, and rushing streams. Summer brings rain and mist that veil the surrounding peaks in mystery, while on clear days, the majestic, snow-capped mountains are visible in the distance. This area is quite different from the heart of the Qinghai-Tibet Plateau, where dense forests and lush grasslands are rare at the same altitude. The streams also provide ample pebble resources, ideal for tool-making. It’s easy to imagine that when humans first entered Daocheng, they saw herds of animals roaming freely, unafraid of hunters. Here, there was no scorching heat and annoying insects, only abundant water and grass—a true paradise. For those only stopping in Daocheng in the summer, it must have seemed ideal.

In my book Prehistoric Modernization, I devoted a chapter to prehistoric culture on the Qinghai-Tibet Plateau. Considering the cultural and ecological conditions, I argued that groups capable of effectively utilizing the plateau might have been agriculturalists, not hunter-gatherers. The primary productivity of the Qinghai-Tibet Plateau is extremely low, similar to that of the Arctic, with very sparse resources and none of the rich avian or other marine resources found in the Arctic coastal areas. Furthermore, high altitudes limit human mobility. Hunter-gatherers rely on mobility for food, with the Arctic peoples utilizing sleds, canoes, and consuming energy-rich food sources like seals—resources absent from the Qinghai-Tibet Plateau. Sustainable habitation on the plateau would therefore require agricultural support. Linguistic, physical anthropological, DNA, and archaeological evidence all support the theory that the Tibetans who currently inhabit the plateau only arrived in the Neolithic era, with sustained use of the plateau beginning in that period.

Nonetheless, I underestimated the efforts of Paleolithic humans to explore the Qinghai-Tibet Plateau. Before the Piluo site was discovered, the Nwya Devu site in the Plateau’s heartland provided evidence that modern humans ventured into the high-altitude Plateau over 30,000 to 40,000 years ago. The Piluo site shows that, in addition to modern humans, pre-modern humans also managed this feat. They entered these high altitudes at least four times, with the earliest dating back 200,000 years. Could these hunter-gatherer groups remain on the plateau year-round? Technically, the plateau imposes a “ceiling” on the sustainability of the hunter-gatherer lifestyle, as these groups need to secure a stable food supply within a manageable range. On the plateau, with sparse vegetation and limited animals, people would need to expand their range to obtain enough food, but the thin oxygen levels restrict their mobility. These compounded challenges significantly lower the “ceiling” of subsistence. Winters would have posed particular difficulties, with resources even scarcer and survival relying heavily on adequate resources. It is in this sense that I argue sustained habitation would be impossible on the Qinghai-Tibet Plateau without agriculture (or animal husbandry).

This challenge is somewhat akin to the story of human migrations out of Africa. About six million years ago, human ancestors diverged from chimpanzees and began their evolutionary journey. Based on current archaeological data, humans first left Africa over two million years ago, and the Eurasian continent was then home to Homo erectus. About 100,000 years ago (though the exact timeline remains debated), modern humans left Africa again. By 50,000 years ago, they had spread to East Asia, absorbing some genes from indigenous groups and forming the later East Asian populations. This basic framework suggests that there have been at least two major dispersals in human history. The Homo erectus populations on the Eurasian continent ultimately disappeared. The Neanderthals and Denisovans who lived contemporaneously with modern humans had explored high latitudes and high plateaus, but they also vanished into prehistory. In the last 200,000 years, different human groups, including modern humans, were drawn to this uncharted land and repeatedly ventured onto the plateau. However, in terms of sustaining life, it was difficult for hunter-gatherers to survive through the harsh winters and maintain population densities sufficient to reproduce. From a grand history perspective, these early efforts were not entirely futile; they contributed to genetic adaptation for high-altitude living, laying the foundation for later success.

Exploration is innate to humans, and part of life itself. Venturing into Piluo, one can witness the efforts of Paleolithic humans to explore the Qinghai-Tibet Plateau. It’s a saga filled with a sense of heroism and resilience. This indomitable spirit led humanity to venture out of Africa, traverse the world, climb the Himalayas, and cross the oceans, ultimately reaching every corner of the Earth. Today, Chinese research teams are advancing archaeological work on the Qinghai-Tibet Plateau, with multiple disciplines collaborating and a growing number of young researchers joining the effort. Why are they doing this? Perhaps it’s for the challenge, the allure of unsolved mysteries, and because we just want to know.

Chen Shengqian is a professor from the School of History at Renmin University of China.

Edited by REN GUANHONG