Metal resources and Han immigrants: Lead isotope analysis of metal relics excavated from Heimajing cemetery in Gejiu, Yunnan, China

The Heimajing cemetery of the Han Dynasty is in southwestern China's most famous tin-mining area. Smelting relics, such as tin ore and lead ingots, unearthed from Heimajing cemetery indicated the people were probably involved in mining and smelting. We used chemical composition and lead isotope analyses to study 76 samples from bronze artifacts and metallurgical remains. The results show that Han-style bronzes, such as bronze hu, pan, ear cups, and other household utensils, as well as coins, are mainly lead–tin bronzes, while Southwest barbarian-style objects such as spears, ge, and chu are copper or tin–bronze. Lead isotope analysis shows that these bronzes and metallurgical remains were mainly produced locally using the mineral sources of the Gejiu region. Not only are Heimajing bronzes stylistically similar to Han-style bronzes of the Lingnan region, but also the source of the bronze material in both places is the same, both from the local mine in Gejiu. We speculate that the mining and metallurgical activities of metal mineral resources in Gejiu attracted many people from Lingnan. Then, they transported raw metal materials to the outside world, so Gejiu quickly became a center for supplying lead and tin raw materials during the Han Dynasty. Lead and tin sources from Gejiu have been transported to the Yungui Plateau, Lingnan, and Southeast Asia.