Human Presence in the Southeastern Tibetan Plateau after the Last Glacial Maximum

The Tibetan Plateau (TP) is a critical region for understanding patterns of human occupation due to its hostile environment. Numerous archaeological sites have been reported on the plateau, except in its southeastern part. Here, we present new findings from the Congqiancuo area, located in the Haizishan Mountain in southeastern TP, characterized by a glacial landscape. Lithic artifacts were found on the ground surface and in a test pit on the low terrace of Congqiancuo lake, a moraine-dammed lake. The artifacts mainly consist of medium- to small-sized flakes and debris. The excavated section, with a depth of 1.3 m, comprises four layers, with artifacts found in Layers 3 and 2. Luminescence dating was performed on quartz and K-feldspar grains, and radiocarbon dating was carried out on charcoal samples. The results show that only ~ 0.18 – 0.6‰ of quartz grains are bright enough for dating, while almost all K-feldspar grains can be used. The reliability of the luminescence ages is indicated by the consistency of quartz and K-feldspar ages, while the radiocarbon ages on charcoal fragments are anomalously young. The luminescence ages were further refined using Bayesian statistical model. The results indicate that the sample from the bottom layer (Layer 4) was dated to 17.7 ± 1.9 ka, immediately following the recession of glaciers at 18.1 ± 1.4 ka. The cultural layers (Layers 3 and 2) were deposited between 13.8 and 4.2 ka. Sediments from a similar depth as the bottom artifacts were dated to ~11.8 ka, suggesting the beginning of human occupation in this area. The grain-size distribution and magnetic susceptibility of the sediment samples were analyzed. Their results and sedimentary properties indicate that ancient humans lived on the shore of the moraine-dammed lake during a relatively warm climate. This finding implies that southeastern TP was also an important area for human settlement and activity immediately following the Last Glacial Maximum.