This bronze mirror was made in Japan during the Kofun period (Ca. 3rd–7th c.) using Chinese-made mirrors as a model. It was unearthed from a tumulus, a mound of earth piled up to create a grave. The face you can see is the back of the mirror, not its reflective surface. The projection in its center is a knob for passing a cord through. Can you see the four outlines slightly resembling curled-up caterpillars around it? These are the tuolong from which the mirror gets its name. Tuolong are mythical Chinese beasts. Their heads actually overlap with depictions of the upper bodies of Chinese deities. The tuolong also have rod-like objects clutched in their mouths. All these details combine to make this an extremely complex design. Only the rulers of Yamato, based in the Kinki region, would have possessed the technology to create a mirror like this one.

This mirror, however, was found far from the Kinki region, in the Yanai Chausuyama Tumulus, which faces the Seto Inland Sea in southeastern Yamaguchi Prefecture. Two boys accidentally discovered this tumulus in 1892. Later, the site underwent extensive excavation, and a 90-meter-long keyhole-shaped tumulus was uncovered. Approximately 10 kilometers from the Chausuyama Tumulus is another gigantic tumulus known as the Shiratori Tumulus. In ancient times, there was a waterway for boat traffic on the line between these two tumuli. The tumuli were positioned at the entrance and exit of this waterway. The shipping route to the Korean Peninsula via the Seto Inland Sea was vital to the Yamato authorities in terms of trading with mainland Asia. The Yamato authorities made alliances with the rulers of these two areas to ensure safe passage for ships and gave them bronze mirrors and other gifts as symbols of those alliances. This bronze mirror is 45 centimeters in diameter and weighs nearly 9 kilograms. It is the largest Kofun-period Japanese mirror. The size of a mirror is thought to be an indication of its class, so the size of this one highlights the importance of the region in the eyes of the Yamato authorities.