Source and Role of Bronze Coins in Maritime Trade During the Song (960–1276  ad ): Focus on New Discoveries of Underwater Copper Metal Relics in the South China Sea

In the 1440s, a boom in copper production in northern Guangdong supported the establishment of a mint called “Yongtong‐jian (YTJ)” near the copper mine, promoting the unprecedented prosperity of maritime trade. However, our understanding of the importance of the YTJ mint in the Age of Discovery is still very limited. We conducted a scientific analysis of 44 underwater Song coins and bronze ingots recovered from the Beijiao site in the South China Sea via ED‐XRF, metallography and MC–ICP–MS. We compared the differences in the chemical and Pb isotopic compositions among the coins, ingots and ores, as well as the Kamakura Buddha of Japan. For the first time, the coins and YTJ, as well as the ingot and the Buddha, were linked. These findings open new avenues for research into medieval marine history and the role of the Chinese currency in the formation of overseas monetary systems.