Artifacts Excavated from Takeshima Kofun in Yamaguchi

A Set of Grave Goods From a Lost Island Tomb

In 1888, a landowner clearing ground on a small island in Tokuyama Bay cut into a stone chamber at the summit of an old burial mound. Inside lay bronze mirrors, sword blades, arrowheads and an iron axe that had rested there since the early Kofun period, roughly the third to fourth century. The mound, called the Takeshima Gokarō Yashiki Kofun, was a keyhole-shaped tomb about 56 meters long. The island that held it, off the coast of present-day Shūnan in Yamaguchi Prefecture, has since been absorbed by land reclamation and now forms part of the mainland.

For decades the objects passed down through the finder and his family. They are kept today at the Kyushu National Museum in Dazaifu, Fukuoka, and as a group they were designated an Important Cultural Property in 1988.

Recorded as a single lot, the set brings together two triangular-rimmed deity-and-beast mirrors (sankakubuchi shinjūkyō), one picture mirror showing deities, human figures, a chariot and horses, four swords and blade fragments, twenty-six bronze arrowheads, a single iron axe and one iron arrowhead. The preservation is uneven, yet the combination records the standard furnishing of an early Kofun chieftain's grave with unusual completeness.

A Mirror That Carries a Date

One of the two triangular-rimmed mirrors is broken into small pieces, but along its rim runs an inscription, and within it survives a Chinese reign name: Zhengshi, read Seishi in Japanese. The first year of Zhengshi corresponds to 240 CE.

That date matters. According to the Chinese chronicle known as the Records of Wei, Queen Himiko of Wa sent envoys to the Wei court, and the Wei emperor sent gifts in return that included one hundred bronze mirrors. The return mission reached Wa in 240. A mirror bearing the Zhengshi reign name therefore raises a question that has occupied Japanese archaeologists for generations: could this be one of those hundred mirrors? The idea is a hypothesis rather than a settled fact, and scholars still debate where these mirrors were actually cast, since no triangular-rimmed mirror of this kind has ever turned up in China itself.

The Takeshima mirror has a second importance, less famous but more concrete. Two other mirrors cast from the same mould survive, one from the Kanizawa tomb in Gunma and one from the Morio tomb in Hyōgo. On the Kanizawa mirror the first character of the reign name is missing; on the Morio mirror the inscription is gone entirely. The Takeshima example preserves the part the others lack, which let researchers read the reign name and fix the date of the whole group. For a field that rarely gets firm calendar dates from prehistoric Japan, that single legible line counts for a great deal.

The other triangular-rimmed mirror, marked with the phrase "Tennō jitsugetsu" and a band of beast figures, belongs to a wider family: identical castings are known from the Tsubai Ōtsukayama tomb in Kyoto, the Hakusan tomb in Kanagawa and the Kamikura tomb in Fukuoka. The picture mirror, signed "made by Liu," is rarer, with close parallels only at the Kagamidō tomb in Ōita and the Tenjinyama tomb in Nara. These same-mould links describe a network. One mirror, struck from a single mould, ended up in tombs scattered from Kyushu to eastern Japan, which many researchers read as evidence that an emerging central power, the early Yamato court, handed out prestige mirrors to allied chiefs across the islands.

What to Look For at the Museum

The Kyushu National Museum holds the set, and pieces from it appear in the Cultural Exchange Exhibition, the permanent display on the fourth floor that follows Japanese history from the Paleolithic to the Edo period. The galleries rotate their contents, so the dated mirror is not always out; checking the current display before a visit is worthwhile.

These are small, quiet objects, and the reward comes from looking closely rather than from scale. On a triangular-rimmed mirror, the rim really is triangular in cross-section, a profile that sets this type apart from every other ancient mirror found in Japan. Around the central knob, winged immortals and sacred beasts alternate in a fixed rhythm; line up your eye with the figures and you can tell which way the mirror was meant to be read.

The casting is fine. On a well-preserved face you can still follow individual characters of the inscription that circles the design. On the dated mirror, look for the few graphs surviving near the broken edge. Those are the marks that pinned a year onto the third century.

When they share a case with the weapons from the same chamber, the corroded blades, the ring-pommel sword fragment, the clustered arrowheads, the objects read less like separate exhibits than like the contents of one grave, gathered for a single person more than sixteen centuries ago.

Getting There and What Is Nearby

The Kyushu National Museum stands on a wooded ridge directly behind Dazaifu Tenmangū, the shrine to Sugawara no Michizane, the Heian-era scholar revered as a deity of learning. The two are joined by an access tunnel, a long moving walkway and escalator that shifts color as you ride it; the passage takes only a few minutes. From Nishitetsu Dazaifu Station the walk runs about ten minutes, up a shrine approach lined with shops selling grilled umegae-mochi, the local plum-stamped rice cakes.

Opened in 2005 as Japan's fourth national museum, after Tokyo, Kyoto and Nara, the building was conceived around the idea of seeing Japanese culture through its exchanges with the rest of Asia, a fitting frame for a mirror set that ties a Yamaguchi island to the courts of mainland China. The shrine draws students before their exams, and its grounds hold thousands of plum trees that flower from late winter into early spring.

From central Fukuoka, the museum is reachable from Nishitetsu Fukuoka (Tenjin) Station by train via Nishitetsu Futsukaichi, or by the direct Tabito liner bus from Hakata. Admission to the Cultural Exchange Exhibition is modest, and special exhibitions are charged separately.