Ironworking Connections between Korea and Japan: Rethinking the Origins of Japanese Furnaces

This study compares ancient blast furnaces in the Korean Peninsula and the Japanese archipelago from structural and technological perspectives to elucidate the adoption and development of iron production technologies in Japan. While research on the origins of iron production is generally limited by scarce archaeological evidence, the systematic excavation and analysis of furnaces in these regions allow for detailed investigation of technological lineages and transmission patterns. Key furnace features—including bellows systems, arrangement structures, construction methods, and plan layouts—were analyzed to compare technological attributes and operational methods. The results indicate two distinct developments. Japanese box-shaped furnaces exhibit orthogonal bellows and arrangement directions and require external extraction of interior iron bloom, resulting in low operational efficiency. In contrast, Korean cylindrical furnaces show aligned bellows and arrangement directions, enabling higher productivity and sustained operation. Box-shaped furnaces appear to have evolved independently through the fusion of local Japanese refining techniques and partial information from Korean technology. The ground-type cylindrical furnaces of northern Kyushu share structural and technological similarities with Korean cylindrical furnaces but developed gradually under regional social, economic, and technological conditions, reflecting partial influence rather than direct transmission. These findings demonstrate that iron-smelting technologies in Japan were not merely transplanted from abroad but selectively adapted and transformed within specific local contexts. By grounding the analysis in structural archaeology, this study provides a nuanced understanding of technological interaction, adaptation, and innovation in early East Asia, and offers a foundation for future comparative research on ancient metallurgical systems.