Highly radiogenic lead in shandong bronzes (5th-3rd century BC) and lead mines provides evidence of a metal road from China to Korea and Japan

The origin of the lead materials containing highly radiogenic lead (HRL) isotopes found in bronzes dating back to the 4th–2nd century BCE in Korea and Japan remains enigmatic. The lead isotope analysis conducted on 111 bronzes, slags, and lead ores from Shandong, China, has provided valuable insights into the establishment of the metal trade network in Northeast Asia. The findings reveal a notable transition in the source of lead material used in Shandong from the early to the middle and late Warring States periods. Initially, Shandong bronzes heavily relied on imported lead materials from Central China; however, during the middle and late Warring States periods, there was a shift towards the utilization of HRL (²⁰⁶Pb/²⁰⁴Pb range: 18.6–23.1) and lead with low ²⁰⁶Pb/²⁰⁴Pb ratios, which were uncommon in other regions of China contemporaneously. The isochron relationship (2.29 Ga) between the ²⁰⁷Pb/²⁰⁴Pb-²⁰⁶Pb/²⁰⁴Pb of the HRL bronzes from Shandong, Japan-Korea, and the HRL lead ores of the Xiliang lead mine in Yishui, Shandong, demonstrates a strong correlation, suggesting that the HRL metal materials prevalent in Northeast Asia during the 4th–2nd century BCE likely originated from the Tai-Yi Mountains in Shandong Province.