Composition and Technology of a Unique Bohai Bronze Mirror from Kraskino Walled Town (Southern Primorye, Russian Far East): An Interdisciplinary Study

This paper presents the results of a comprehensive study of a bronze mirror discovered during archaeological excavations at the Kraskino Walled Town (Khasansky District, Primorsky Krai), dating to the Bohai State period (698–926 AD). This object is the only intact Bohai-period mirror found in Primorye and serves as a valuable source of information on the origins, manufacturing techniques, and socio-economic context of metalworking in the Bohai State. The research employed an interdisciplinary approach. A combination of analytical methods (X-ray fluorescence analysis, scanning electron microscopy, and Fourier-transform infrared spectroscopy) revealed that the mirror was made of high-tin bronze (Cu ~50%, Sn ~25%) with silver and lead additives. The observed dendritic structure of the alloy and technological defects indicate that the object was cast without subsequent heat treatment. The unique decoration—a blooming cherry motif executed in repoussе and point engraving techniques—has no direct parallels in Bohai or neighboring cultures. Notable evidence of metal recycling including the presence of silver and heterogeneous lead distribution suggests the object may have been recast, potentially incorporating imported items. This corresponds with documented trade relations between Bohai and China, Japan, and Korea. Nevertheless, the mirror’s distinct combination of local artistic motifs and technical attributes confirms its production within Bohai’s indigenous craft tradition. This study constitutes the first comprehensive scientific analysis of a complete Bohai-period bronze mirror from Primorye. The findings provide substantial new insights into bronze-casting technologies employed by the Bohai State.