Discovery of bladelet technology on the Tibetan Plateau and the activity history of hunter-gatherers during the Last Deglaciation

The Tibetan Plateau, with an average elevation exceeding 4000 m, presents one of the most challenging environments for human survival due to its extreme cold, hypoxia, and variable climate. Archaeological evidence demonstrates a deep history of human exploration and adaptation on the plateau, beginning with archaic hominins like the Denisovans in the Middle Pleistocene. The large-scale peopling of the high-altitude interior is mainly associated with the spread of Homo sapiens employing microblade technology, characterized by the production of standardized microblades from elaborately prepared cores like wedge-shaped and semi-conical forms. The advanced microblade technology facilitated human dispersal across the plateau after the Last Glacial Maximum. Currently, more than 110 microblade sites have been discovered, and the lithic technologies at these sitesshow strong typo-technological affinities with those from North China, suggesting a major dispersal route via the plateau’s northeastern corridors. This paper reports new findings from Locality 3 of the Shanggangang site in the hinterland of the plateau, revealing a previously unrecognized lithic tradition during the terminal Pleistocene. Shanggagang Locality 3 is located in the Qiusang River Valley near Lhasa, Xizang, at an elevation of ~4140 m, and it was systematically excavated in 2024. Stratigraphic analysis and absolute dating of both charcoal (14C) and sediment (optical dating) samples constrain human activity to approximately 13000–10000 years ago. The lithic assemblage, comprising 603 artifacts, reveals two distinct reduction systems. One is the bladelet technology centered on burin-core reduction strategy. A total of 35 burin-cores has been identified. The blank of these cores were primarily made on chert flakes or chunks, and the size of them is small (avg. 27.5 mm×19.5 mm×10.9 mm). The platforms of burin-cores were often prepared, and bladelets were serially detached along the acute intersection (ridge) of two surfaces of the blank using direct percussion. The resulting bladelets are less standardized in form and dimensions compared to typical microblades produced by pressure or indirect percussion. This system coexists with an expedient reduction strategy utilizing locally available cobbles (mainly igneous rocks) for producing flakes, and in some cases, elongated flakes were detached from discoidal and multifacial cores. The technological signature of Shanggagang Locality 3 is clearly different from contemporaneous microblade sites on the interior plateau, such as Nwya Devu Locality 3 (~11–10 ka), and sites surrounding the Qinghai Lake. These sites are mainly featured by wedge-shaped and semi-conical microblade cores. Shanggagang Locality 3 constitutes the first securely dated and well-contextualized discovery of a burin-core based bladelet technology in the hinterland of the Tibetan Plateau. The emergence of this distinct technology during the Last Deglaciation, a period of significant climatic fluctuation including the Younger Dryas cold episode, underscores the ability and diversity of technological strategies employed by foraging groups navigating the high-altitude environment. While microblade technology on the plateau likely originated from North China, the origins of the burin-core bladelet technology at Shanggangang remain unclear. This discovery updates our understanding of late Pleistocene lithic technology on the Tibetan Plateau. It demonstrates that diverse technological traditions, which potentially represent distinct cultural or demographic dynamics, were present on the plateau during the early occupation phase by Homo sapiens. Future research, including detailed techno-functional analysis of the burin-cores and broader regional comparisons, is essential to trace the origins of this technology and to elucidate the intricate patterns of migration and interaction among late Pleistocene populations on the “Roof of the World”.