The Hanzhong basin in southern Shaanxi, a corridor between the Shang Central Plains, the Chengdu Plain, and the middle Yangtze, has yielded more than 700 bronzes from some 33 caches and hoards of the local Baoshan Culture (roughly fourteenth to eleventh centuries BCE). Compositional and lead-isotope studies argue that an indigenous metallurgical industry existed alongside imported Shang and regional metalwork, but three linked questions posed by the 2016 compositional study remain open: (1) no direct archaeological evidence for metallurgical production sites (workshops, furnaces, slag, mining) has been found in the basin, so indigenous production is still a hypothesis supported only by analysis of the finished objects; (2) the origin of the small number of tin-bronze sickles and Zhang sceptres — imported Shang metal or local manufacture from arsenic-rich materials — is unresolved, a question entangled with the contested provenance of the highly radiogenic lead identified in Hanzhong metal by later lead-isotope studies; (3) the purpose of the numerous caches and hoards, and the social context in which bronzes were acquired, deposited, and exchanged, remain unexplained.

Background

The Hanzhong basin, in the upper Han River valley of southern Shaanxi Province, China, lies between the Qinling Mountains to the north and the Daba Mountains to the south, linking the Central Plains — heartland of the Shang dynasty (c. 1600–1046 BCE) — with the Chengdu Plain (home of the Sanxingdui and Jinsha bronze cultures) and the middle Yangtze region. Since the 1950s, dozens of bronze caches and hoards (buried deposits of metal objects, mostly found accidentally by farmers rather than archaeologically excavated) have come to light around the confluence of the Han and Xushui Rivers, yielding more than 700 objects from 33 caches at 19 sites. This 'Hanzhong' or 'Chengyang' bronze group belongs to the local Baoshan Culture and includes weapons, ritual vessels, masks, Yang discs (ring-shaped objects), Zhang sceptres (ceremonial blade-like implements), sickle-shaped objects, and tools. Electron probe microanalysis (EPMA, a microanalytical technique measuring the chemical composition of small sample areas) of more than 200 objects showed that the vessels and weapons are largely tin or leaded-tin bronzes typical of Shang-period metallurgy, while the typologically local forms — sickle-shaped objects, Zhang sceptres, and socketed axes — are made mostly of unalloyed copper or 'natural alloys' containing arsenic, antimony, and nickel, impurity patterns that reflect specific ore types rather than deliberate alloying (Chen et al. 2009; Mei et al. 2009; Chen et al. 2016). Lead isotope analysis (LIA), the standard provenance method comparing isotope ratios such as 206Pb/204Pb^{206}\mathrm{Pb}/^{204}\mathrm{Pb} in metal and ore, shows that a large share of Hanzhong bronzes, including many of the local forms, contain highly radiogenic lead (HRL) — lead with unusually high uranogenic isotope ratios derived from ancient uranium-rich ores — whose geological source is a long-standing unsolved puzzle for Shang-period China as a whole. On the basis of these compositional data, Chen, Mei, Rehren, and Zhao (2016) argued that an indigenous metallurgical industry existed in Hanzhong, with imported objects coming from the Wei River valley, the middle Yangtze, and the Shang Central Plains; a later LIA study by the same group found the local-form objects to be predominantly HRL-bearing unalloyed copper and proposed the Qinling area as a possible HRL source, while stressing that this remains a working hypothesis (Chen et al. 2019). Direct smelting evidence of the kind that would settle such questions — furnace slag demonstrably derived from arsenical copper smelting — has been excavated at Laoniupo in central Shaanxi (Chen et al. 2017), but nothing comparable is known from the Hanzhong basin itself. The 2016 study closed by listing the questions that remain unanswered, which define this problem.

Problem Statement

The problem is to assess, on the evidence available in the published compositional, isotopic, and archaeological record, whether and how an indigenous bronze industry operated in the late second-millennium BC Hanzhong basin, and how bronzes circulated and were deposited there. As posed by Chen et al. (2016), it comprises three linked components that jointly support this single objective: (1) Production sites: assess what the compositional and isotopic evidence from the finished objects does and does not establish about an indigenous industry in the basin, and specify which direct archaeological evidence of metallurgical production — workshops, furnaces, casting moulds, slag, or mining — reliably dated to the Shang period would confirm or refute it and fix the location and scale of the hypothesized indigenous industry. (2) Metal origin of the diagnostic local forms: determine whether the small number of sickles and Zhang sceptres that appear to be made of tin bronze were produced from imported Shang metal (for example, bronze vessels looted or otherwise acquired and re-melted) or were made locally from materials with a different, arsenic-rich trace-element signature. (3) Hoards: explain the purpose of the numerous caches and hoards and the social context in which bronzes were acquired, deposited, and exchanged in Hanzhong — including whether large hoards such as Sucun Xiaozhong represent bronzes acquired in a single event, and if so why such a quantity was imported.

References

  1. Kunlong Chen, Jianjun Mei, Thilo Rehren & Congcang Zhao (2016). Indigenous production and interregional exchange: late second-millennium BC bronzes from the Hanzhong basin, China. Antiquity 90(351), 665–678. DOI: 10.15184/aqy.2016.94. https://doi.org/10.15184/aqy.2016.94
  2. Kunlong Chen, Thilo Rehren, Jianjun Mei & Congcang Zhao (2009). Special alloys from remote frontiers of the Shang Kingdom: scientific study of the Hanzhong bronzes from southwest Shaanxi, China. Journal of Archaeological Science 36(10), 2108–2118. DOI: 10.1016/j.jas.2009.04.016. https://doi.org/10.1016/j.jas.2009.04.016
  3. Jianjun Mei, Kunlong Chen & Wei Cao (2009). Scientific examination of Shang-dynasty bronzes from Hanzhong, Shaanxi Province, China. Journal of Archaeological Science 36(9), 1881–1891. DOI: 10.1016/j.jas.2009.04.017. https://doi.org/10.1016/j.jas.2009.04.017
  4. Kunlong Chen, Siran Liu, Yanxiang Li, Jianjun Mei, Anding Shao & Lianjian Yue (2017). Evidence of arsenical copper smelting in Bronze Age China: a study of metallurgical slag from the Laoniupo site, central Shaanxi. Journal of Archaeological Science 82, 31–39. DOI: 10.1016/j.jas.2017.04.006. https://doi.org/10.1016/j.jas.2017.04.006
  5. Kunlong Chen, Jianjun Mei, Thilo Rehren, Siran Liu, Wei Yang, Marcos Martinón-Torres, Congcang Zhao, Yoshimitsu Hirao, Jianli Chen & Yu Liu (2019). Hanzhong bronzes and highly radiogenic lead in Shang period China. Journal of Archaeological Science 101, 131–139. DOI: 10.1016/j.jas.2018.11.010. https://doi.org/10.1016/j.jas.2018.11.010
  6. Y. Z. Zhangsun, Z. Y. Jin, F. Z. Feng, J. H. Tian, H. G. Wang, C. C. Zhao, F. Huang & X. T. Wu (2021). Revisiting the lead isotopic compositions of the Shang bronzes at Hanzhong and the new hypothesis of Qinling as the source of highly radiogenic lead. Archaeometry 63(1), 122–141. DOI: 10.1111/arcm.12630. https://doi.org/10.1111/arcm.12630
  7. R. Liu, Y.-K. Hsu, A. M. Pollard & G. Chen (2021). A new perspective towards the debate on highly radiogenic lead in Chinese archaeometallurgy. Archaeological and Anthropological Sciences 13, article 33. DOI: 10.1007/s12520-021-01280-w. https://doi.org/10.1007/s12520-021-01280-w
  8. Ruiliang Liu & A. Mark Pollard (2022). Asking different questions: highly radiogenic lead, mixing and recycling of metal and social status in the Chinese Bronze Age. Mineralogical Magazine 86(4), 677–687. DOI: 10.1180/mgm.2022.32. https://doi.org/10.1180/mgm.2022.32
  9. Qingzhu Wang, Siran Liu, Jianli Chen, Yanxiang Li, Jianfeng Lang, Xiaodong Guo, Xuexiang Chen & Hui Fang (2023). The first discovery of Shang period smelting slags with highly radiogenic lead in Yingcheng and implications for the Shang political economy. Journal of Archaeological Science 149, article 105704. DOI: 10.1016/j.jas.2022.105704. https://doi.org/10.1016/j.jas.2022.105704
  10. Siran Liu, Zhenfei Sun, Ji Zhang, Junling Lin, Kunlong Chen, Jianli Chen, Jianfeng Cui & Jianjun Mei (2025). 50 years of bronze provenance studies: A perspective from China. Journal of Archaeological Science 180, article 106272. DOI: 10.1016/j.jas.2025.106272. https://doi.org/10.1016/j.jas.2025.106272
  11. Junling Lin, Zhenfei Sun & Siran Liu (2026). Revisiting the Pb content threshold for copper provenance investigation in Early Bronze Age China. Journal of Archaeological Science 190, article 106548. DOI: 10.1016/j.jas.2026.106548. https://doi.org/10.1016/j.jas.2026.106548
  12. Xuekai Qi, Ruru Chen, Chengwei Wang, Yue Li, Fei Tang, Zhenbin Xie, Honglin Ran, Qing Xiao, Yulai Chen, Ruoyu Shi, Ganyu Zhang, Chong Wang, Furen Hou, Matthew Collins & Rui Wen (2026). Protein evidence for animal sacrifice and shared ritual practices in Bronze Age Sanxingdui, Southwest China. Journal of Archaeological Science 192, article 106591. DOI: 10.1016/j.jas.2026.106591. https://doi.org/10.1016/j.jas.2026.106591