On October 12, during an archaeological dig at the Bai Ren Cheng site in Xingtai, Hebei Province, Wu Xiaotong, a lecturer at Renmin University of China’s History Department, shared intriguing insights. “Based on the ‘Bai Ren’ knife coins we collected from the site, it suggests that during the Warring States period, the Zhao state engaged in metal trade with various nations.”
The Bai Ren Cheng site, covering an area of 4 million square meters, is recognized as one of the best-preserved ancient city ruins in China. In the Warring States period, it served as the second-largest city in the Zhao state until it was abandoned during the Tang Dynasty due to flooding.
Previously, the Longyao County Cultural Relics Protection Management Office uncovered a popular type of copper knife coin from the Warring States era, which featured the inscription “Bai” (referring to “Bai Ren”).
On October 10, the Longyao County office showcased the “Bai Ren” knife coins collected during earlier excavations. Wu noted, “At that time, the Zhao state primarily circulated two main currencies: ‘Gan Dan’ and ‘Bai Ren.’ The ‘Gan Dan’ coins were minted in Zhao’s capital, Handan, while the ‘Bai Ren’ coins were likely produced at the Bai Ren Cheng site, underscoring its significant economic role.”
To analyze the manufacturing process and raw material origins of the “Bai Ren” knife coins, researchers examined their alloy composition, which revealed that the coins were made from a copper-tin-lead alloy. “Copper accounts for about 60%, tin about 10%, and lead approximately 27%, which is very similar to the alloy composition of the ‘Gan Dan’ coins,” Wu explained, highlighting the strict minting standards of the Zhao state, where various cities utilized the same alloy formula.
Additionally, Wu employed lead isotope ratio analysis to trace the sources of the lead used in the “Bai Ren” coins and discovered that two of the coins originated from different lead sources. “This indicates a diversification of raw materials for coin minting in the Zhao state, suggesting active metal trading with other nations, specifically aligning with coins from Wei, Chu, and Yan Qi.”
Wu emphasized that during the Warring States period, each state had unique metal resources. While the Zhao state had abundant iron ore and a robust iron industry, copper and lead resources were relatively scarce, necessitating imports from other regions or countries. “The discovery of the ‘Bai Ren’ knife coins reinforces this point.”
The Bai Ren Cheng site has undergone several excavations since 2016, with the current dig being the fifth. Li Fang, the head of the Longyao County Cultural Relics Protection Management Office, explained, “The combined area excavated over five attempts totals 3,600 square meters. The first dig was a test in a corner, while the third and fourth digs uncovered substantial Han Dynasty remains in six layers of deposits, indicating a prosperous period for the city.”
Li concluded, “Current excavations suggest that the area explored between 2022 and 2024 is a rich core zone of cultural deposits at the Bai Ren Cheng site.”
