The Ma’anshan site is located on the second terrace of the Sanggan River, Nihewan Basin, and is an important locality of the Hutouliang site group. Excavations in 1997-1998 revealed multiple occupational horizons and tens of thousands of lithics and faunal remains, including 3549 pieces of labeled specimens, together with dozens of fireplaces and a unique structure resembling a storage pit. The original cultural layer (Layer 3) is further divided into 6 sublayers (layers 3A-3F). AMS radiocarbon dates with Bayesian analysis suggest the site was dated approximately 17-15 ka cal BP. The microblade industry at the site mostly exploited Yubetsu technology, with the toolkit containing side- and end- scrapers, notches, denticulates, burins, bifaces, adze-shaped tools and spearheads. Raw materials were dominated by volcanic breccia, while siliceous mudstone, flint and chalcedony were also important components. Faunal remains were relatively limited in number, and most identifiable pieces recognized as medium-to-large sized angulates, such as Bovidae and Equidae. For bone tools and ornaments, there were several ostrich shell beads and one broken bone awl.
Based on its stratigraphy, dates, features and artifacts, cultural development at the Ma’anshan Site can be divided into two stages. The early stage (sublayers 3F-3B, 17.1-16.3 ka cal BP) was dominated by Yubetsu microblade technology, and around 1/3 of the tools were unifacially or bifacially worked. Volcanic breccia made up over 85% of all raw materials, while flint composed less than 5%. The density of artefacts was extremely high, and activities were well-organized, centering around fireplaces. This settlement pattern suggested that the site was a central base camp of the Hutouliang site group during this time. During the late stage (sublayer3A, 15.8-15.0 ka cal BP), there was an obvious rise of non-Yubetsu methods of microblade production, and end scrapers became more important in the tool assemblage. At the Yujiagou site, which was close to and dated to a similar period (16-13.8 ka cal BP), new tool types appeared such as a partly polished spearhead, grinding stone and some pottery. Volcanic breccia declined in percentage, composing around 70% of all raw materials, while small flint cobbles increased significantly. The subsistence strategy clearly became more complicated. In layer 3A, a “storage pit” was discovered, which was possibly related to the exploitation of botanic resources. At Yujiagou, juvenile angulates might have been kept for storage.
The prevalence of Yubetsu microblade technology at Ma’anshan demonstrated intimate connection with findings in Northeast Asia, which were very different from microblade sites in southern parts of North China. Microblade cores at the site also differed from those at another, the Erdaoliang site, an earlier site in the Nihewan Basin with boat-shaped microblade cores. This technological preference exhibited human migration and cultural exchange between North China and Northeast Asia, rather than inheritance of previous regional traditions. Several significant changes took place at the Ma’anshan site after 16 ka cal BP, including diversification in technology, complexity in subsistence and decline in mobility. These innovations provide crucial evidence for understanding the trajectory of Paleolithic-Neolithic transition in North China.