Stone tools dating back as far as 45,000 years are offering new clues about a mysterious human presence on the Tibetan Plateau, one of the harshest environments on Earth. A new study suggests the story of Homo sapiens on the Tibetan Plateau may stretch deep into the last Ice Age, although researchers cannot yet determine who made the tools.
Researchers led by Peiqi Zhang reexamined thousands of stone artifacts from Nwya Devu, an archaeological site at an elevation of about 4,600 meters (15,100 feet) above sea level. Their analysis shows that ancient toolmakers used a genuine Upper Paleolithic blade-making system unlike the stone technologies that previously dominated much of East Asia.
The findings raise the possibility that Homo sapiens carried the technology onto the plateau from northern Asia. However, no human remains have been recovered at Nwya Devu, leaving the identity of the toolmakers unresolved.
The site provides rare evidence of human activity in an environment marked by low oxygen, extreme cold, rugged terrain and great seasonal changes.
Blade technology appeared high on the plateau
Nwya Devu lies in Shenzha County in China’s Tibet Autonomous Region, near several lakes and about a kilometer from an exposed slate outcrop.
Archaeologists excavated a 20-square-meter area and recovered thousands of stone artifacts from three sediment layers. The main occupation deposit was initially dated to between 40,000 and 30,000 years ago. More recent dating placed sediments at its base at about 45,000 years old.
That places the activity within Marine Isotope Stage 3, or MIS 3, a period when Homo sapiens populations were expanding across Eurasia. Other archaeological discoveries have increasingly challenged older ideas that prehistoric stone technology in eastern Asia was relatively simple or slow to change.
Researchers analyzed 3,683 stone artifacts, including flakes, blades, bladelets, cores and retouched tools. Nearly all were made from local fine-grained slate.
Toolmakers turned local slate into blades
The assemblage included 600 blades and 94 smaller bladelets. Researchers found clear evidence that toolmakers deliberately shaped stone cores to produce long, narrow pieces.
The manufacturing process included core preparation and maintenance, although the toolmakers generally invested relatively little effort. They frequently used the natural shape and ridges of pieces of slate rather than extensively preparing each core.
Many cores were abandoned after only a few removals despite still containing usable stone. Researchers said the pattern fits a workshop located close to a raw material source. Evidence from other prehistoric sites has similarly shown that early humans deliberately sought out stone sources to make tools.
Finished blades and tools were less common than researchers expected from the number of blade-producing cores. That imbalance could mean people selected useful blades and carried them elsewhere while leaving heavy cores and stone waste at Nwya Devu.
Lightweight tools may have helped high-altitude travel
Such a strategy could have been particularly valuable on the Tibetan Plateau. Moving at high altitude imposes significant physical demands because of low oxygen, cold conditions and difficult terrain. Carrying heavy stone cores would have added to that burden. Blades offered a more portable alternative. They could be carried away from the workshop and modified into tools when needed.
Researchers said blades can potentially serve several purposes, including cutting and scraping, and can form parts of composite tools. Similar blade technologies have been associated elsewhere with highly mobile populations living in cold and open environments.
The study, however, does not establish exactly how the Nwya Devu artifacts were used. Their possible roles in hunting, processing animal hides, or other activities remain hypotheses. The site’s remote position also raises another question: Were people simply visiting the plateau, or were they spending substantial periods there?
Ancient visitors may have returned to Nwya Devu
The nearly complete sequence of stone production suggests people may have repeatedly visited Nwya Devu to obtain slate and prepare tools.
Researchers propose that the site could have served as a logistical stop within a wider system of movement across the plateau. People may have prepared stone there before taking more portable blades and tools elsewhere. Whether those groups permanently occupied the highlands remains unknown.
Other ancient humans also survived the region’s extreme conditions. Evidence from Baishiya Karst Cave indicates that Denisovans lived on the Tibetan Plateau over a long period.
Researchers therefore examined whether Nwya Devu’s unusual technology could reveal where its unidentified toolmakers came from. They compared the artifacts with Initial Upper Paleolithic, or IUP, industries known from Siberia, Mongolia and northern China.
Northern connection raises questions over toolmakers
IUP blade industries are frequently discussed in connection with the expansion of Homo sapiens across northern Eurasia. Nwya Devu shares broad technological similarities with these northern traditions. Yet the new analysis uncovered important differences.
Typical IUP assemblages often contain more bidirectional blade production, carefully prepared striking platforms, specialized core techniques, and certain types of stone points.
45,000-year-old stone tools are revealing a mysterious human presence on the Tibetan Plateau, more than 15,000 feet above sea level.
The blades may point to an early Homo sapiens expansion into one of Earth’s harshest environments but who made them remains unknown. pic.twitter.com/dQPctfYm0y
— Tom Marvolo Riddle (@tom_riddle2025) August 31, 2026
Most of those characteristics are uncommon or absent at Nwya Devu. Its toolmakers relied more heavily on simpler, unidirectional blade production. Researchers therefore stopped short of formally identifying Nwya Devu as an IUP site.
One explanation is that its technology represents a regional form of the IUP that changed as knowledge moved over great distances. Adaptation to the plateau and Nwya Devu’s role as a workshop could also explain some of the differences.
Another possibility is more complicated: the technology may represent a separate movement of blade-making people from northern Asia.
Identity of the ancient toolmakers remains unknown
The lack of earlier blade traditions on the Tibetan Plateau suggests the technology probably arrived from outside the region. But stone tools cannot reveal the biological identity of their makers.
No human fossils have been recovered at Nwya Devu, making it impossible to directly connect the site with Homo sapiens. Other human populations were also present in prehistoric Asia, including Denisovans, whose remains and genetic legacy have been identified across Asia.
Fossil and genetic evidence nevertheless shows that several Homo sapiens lineages lived across northern and eastern Asia during roughly the same period. Researchers say the technology at Nwya Devu could therefore reflect an early Homo sapiens dispersal onto the plateau.
For now, the 45,000-year-old evidence leaves two major questions unanswered: who made the tools and how long did they remain in the highlands? Further archaeological sites and human fossils will be needed to determine whether Nwya Devu records temporary visits, repeated movements, or a more sustained human presence on the Tibetan Plateau.
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