Tin-plated iron armor plates from the Jizhong site in Shaoxing. [Photo/Tide News]

Archaeologists have uncovered China's earliest known tin-plated iron artifacts at the Jizhong site in Shaoxing, Zhejiang province, including large numbers of tin-plated iron armor plates and unfinished pieces dating back to the Wu Dynasty (222-280) of the Three Kingdoms era.

The findings are not only the oldest tin-plated iron objects ever discovered in China, but also the world's earliest known archaeological evidence of a tin-plating industry. They show that more than 1,700 years ago, craftspeople had already developed a systematic process for coating iron with tin.

The discovery fills a long-standing gap in China's metallurgical history. While the country has a rich tradition of bronze tinning and tinware production, there had been no reliable evidence that ancient China produced tin-plated iron domestically. These newly unearthed artifacts confirm that people in present-day Zhejiang had mastered this advanced technology by the Eastern Wu period.

Tin plating protects iron from rust and improves durability. Remarkably, despite being buried for around 1,700 years, many of the armor plates still retain their distinctive silvery metallic sheen, reflecting the sophisticated metalworking skills of ancient Zhejiang. The research was jointly conducted by the University of Science and Technology Beijing and the Shaoxing Institute of Cultural Relics and Archaeology, with the results published in the Journal of Cultural Heritage.