High-precision chronology and scientific analysis of Panchi mirrors reveal the state policy impact in early Imperial China

As one of the most important handicrafts in China during the Warring States period (475–221 BCE) and the Han dynasty (206 BCE – 220 CE), the mirror-casting industry provides a unique source of evidence to understand the response of the bronze production industry to the gradually febrile political-economical ecology and international trade and exchange. This paper focuses on the Panchi mirror, which is a widespread mirror type with long chronology. Systematic analysis is performed on style, inscription, alloying technology, lead isotope ratio and trace element pattern of 40 Panchi mirrors unearthed from Luan region of Southern China, dated to two phases within the Qin to early Western Han dynasties (221-141 BCE). The new data reveals two mirror categories, the first being deeply influenced by Chu-style mirrors and cast by special alloy technology (high lead low tin) and using a short-lived source of lead, and the second marking the start of the well-known Han mirror tradition, characterized by a well-controlled alloying technology (low lead high tin) and more diversified copper sources. The high-precision chronology of the Panchi mirror allows this crucial transformation in the mirror-casting industry to be anchored around the reign of the Emperors Wen (180–157 BCE) and Jing (157–141 BCE), when the early Han state policy of Restoration and Recuperation became fruitful and contributed to a thriving economy, rather than the period of Emperor Wu (141–87 BCE), which is widely accepted as the peak of the Western Han dynasty (202–8 BCE).