Background

The Eastern Tianshan Mountains of Xinjiang, north-western China, have served as a communication junction between the Altai Mountains, the Tibetan Plateau and East Asia throughout human history. While current evidence suggests the early peopling of this region (Yu et al. Reference Yu2018; Feng et al. Reference Feng2021), a scarcity of Palaeolithic/microlithic sites with reliable stratigraphic records leaves the local Palaeolithic cultural framework largely unexplored. Between 2022 and 2024, our investigation identified 108 Palaeolithic/microlithic findspots in the region, collecting a total of 11 522 lithic artefacts. Within Pulei Cave lithic artefacts and well-preserved stratigraphic layers were identified, allowing the first reliable absolute dating of Upper Palaeolithic human activities in the Eastern Tianshan Mountains.

Field investigation

The surface lithic assemblages from the Eastern Tianshan Mountains reveal two dominant techniques, simple core-flake and microblade (Figure 1), both of which were common in China during the Upper Palaeolithic (from c. 50–12 ka; Gao et al. Reference Gao2013; Zhao et al. Reference Zhao, Wang and Walden.2023). The microblade tools can be further classified into three types: the initial microblade technique, the Yubetsu technique and the developed cone-shaped microcore technique (Figure 2). These assemblages, along with the discovery of Levallois-like cores and points and bifacial tools at some microlithic sites, demonstrate the technological complexity of Xinjiang (Figure 2) and differentiate these sites from those of the Bronze and Iron Ages (from c. 4000–2200 cal BP), which are dominated by ground stone tools.

Figure 1. Map showing the geographic setting of the Eastern Tianshan Mountains and the locations of findspots and Pulei Cave (figure by authors).

Figure 2. Lithic artefacts collected from: A) investigated localities (1–8: microblade cores; 9: discoid core; 10 and 13: Levallois-like cores; 11: biface; 12: Levallois point) and B) Pulei Cave (1: flake; 2–3: blades; 4–9: scrapers; 10: adze-shaped object) (figure by authors).

Pulei Cave

Pulei Cave (43°37′23.5″N, 92°23′43.8″E, 2004m), located on the western margin of the Barkol Basin in the north of Eastern Tianshan Mountains, features a half-round entrance 16m wide, opening to the west under a sheer cliff. The interior of the cave forms an irregular space measuring 36.1 × 19.3 × 3.5m (Figure 3A & B).

Figure 3. Images of Pulei Cave: A) aerial photograph of the landscape; B) exterior view; C) north-east corner and the deposits.

The north-eastern corner of the cave retained cultural deposits. Survey of disturbed deposits yielded 19 lithic artefacts and some animal bones (Figure 3C). The south and north walls of the corner are approximately two metres apart, with comparable stratigraphic layers preserved at their bases, measuring approximately 0.5m and 0.7–1.2m in total depth, respectively. Layer 1 is disturbed loess sediment, about 0.2m deep, containing stones and animal bones (Figure 4A). Layer 2 (0.1–0.34m deep) is composed of undisturbed, loose brown soil and also contains animal bones. Layer 3 is another undisturbed loess layer, 0.2–0.4m deep, with some stones; three lithic artefacts and animal bones were collected from the northern portion of this layer (Figure 4B). Layer 4, a sandy layer approximately 0.3m thick, lies beneath the north side of Layer 3 and contains stones and animal bones.

Figure 4. A) Stratigraphic layers from the north-east corner; B) lithic artefacts collected from layer 3 (figure by authors).

Including the two lithic artefacts found outside the cave, a total of 24 lithic artefacts were collected from Pulei Cave: four made of quartzite, 19 of siliceous rock and one of siliceous mudstone. These differ from the rough metamorphic rock found in the cave, suggesting an external source for the raw materials (Figure 2B). The collection includes blades (n = 2), a blade core and tools (n = 13, mostly scrapers and adzes crafted from blades). These features generally indicate an Upper Palaeolithic blade industry, similar to those of the Nwya Devu site on the central Tibetan Plateau (c. 40–30 ka BP; Zhang et al. Reference Zhang2018), the Tolbor-16 site in Mongolia (c. 45 ka BP; Zwyns et al. Reference Zwyns2014) and the Kara-Bom site in the Altai (49–46 ka BP; Rybin et al. Reference Rybin, Belousova, Derevianko, Douka and Higham.2023), characterised by the dominance of the prismatic blade-core technique. This technological consistency suggests that the Eastern Tianshan Mountains were woven into a geographically broad tech-complex and hints at the possibility of population migrations (Derevianko et al. Reference Derevianko, Gao, Olsen and Rybin.2012; Li et al. Reference Li, Chen, Wang and Gao.2016).

Of the animal bones collected from the layers (n = 36) and disturbed deposits (n = 32), 14 pieces could be morphologically identified as deer, hare, equid and small bovids (Figure 5A). Bones from different layers were selected for radiocarbon dating at Lanzhou University (Cao et al. Reference Cao2023). The calibrated radiocarbon dates reveal two periods of deposition during c. 48–27 ka BP and c. 3300–2400 cal BP (Figure 5B). The first period corresponds with the Upper Palaeolithic and aligns with lithic ages reported from neighbouring regions (ranging from 49–30 ka BP). The second period corresponds with an increase in local settlements during the Bronze and Iron Ages. One bone sample (lab code: LZU-241428), found close to the lithic artefacts in layer 3, was dated to 44 727–42 997 cal BP, providing a secure chronological reference for human occupation of the cave. However, the possibility of human occupation during other periods requires further validation in future excavations.

Figure 5. A) Animal remains collected from the cave; B) plot of radiocarbon dates calibrated using the IntCal20 curve (Reimer et al Reference Reimer. 2020) and OxCal 4.4.4 (Bronk Ramsey Reference Bronk Ramsey2009) (figure by authors).