Bronze Bell Excavated from the Kamo Iwakura Site in Shimane

Bronze Bells of Kamo Iwakura: Japan's Greatest Dotaku Discovery

Deep in the forested hills of Shimane Prefecture, an accidental discovery during road construction in 1996 shook the foundations of Japanese archaeology. From a narrow valley in the town of Kamo (now part of the city of Unnan), 39 bronze ritual bells known as dotaku emerged from the earth — the largest number ever found at a single site in Japan. Today designated as a National Treasure, the Kamo Iwakura bronze bells stand as some of the most important archaeological artifacts in the country, offering a remarkable window into the spiritual world of the ancient Izumo region during the Yayoi period, roughly 2,000 years ago.

What Are Dotaku?

Dotaku are bell-shaped bronze ritual objects unique to Japan's Yayoi period (roughly 300 BCE – 300 CE). Their exact purpose remains one of archaeology's enduring mysteries. Some scholars believe they were instruments used in agricultural rituals to pray for bountiful harvests. Others suggest that early, smaller dotaku were "bells to be heard," shaken to produce sound during ceremonies, while later, larger examples evolved into "bells to be seen" — ornamental objects displayed during festivals. Whatever their function, dotaku are among the most distinctive and enigmatic artifacts of ancient Japan.

Approximately 470 dotaku have been discovered across Japan, primarily in the Kinki (Kansai) region and western Japan. The fact that 50 of these have been unearthed from the Izumo area of Shimane Prefecture alone has profound implications for understanding this region's significance in ancient Japan — a significance already hinted at in mythological texts such as the Kojiki and Nihon Shoki.

The Dramatic Discovery

On the morning of October 14, 1996, a heavy machinery operator was excavating a hillside for a farm road in the Iwakura district of Kamo when the equipment struck something unusual with a strange metallic sound. Stopping to investigate, the operator initially thought someone had buried a plastic bucket in the hillside. What he had actually uncovered was the first of 39 bronze bells that had lain undisturbed for approximately two millennia.

The Kamo Town Board of Education was immediately notified, and officials rushed to the scene. By that evening, an emergency press conference announced the discovery to the nation. The site was formally named the Kamo Iwakura Site the following day, October 15.

Over two years of careful excavation from 1996 to 1997, conducted by the Kamo Town and Shimane Prefecture Boards of Education, a total of 39 dotaku were recovered. This number far surpassed the previous record of 24 dotaku found at the Oiwayama Site in Yasu, Shiga Prefecture, making Kamo Iwakura the single most prolific bronze bell discovery in Japanese history.

Why Were They Designated a National Treasure?

The 39 bronze bells were first designated as Important Cultural Properties in 1999 and then elevated to National Treasure status in July 2008. Several factors contribute to their extraordinary historical and cultural value.

First, the sheer quantity is unparalleled. No other site in Japan has yielded as many dotaku from a single burial context, making this assemblage uniquely important for understanding bronze bell production and ritual practices.

Second, the bells span multiple typological periods, from the older Gaien-tsuki Chu Type I to the newer Henpei Chu and Tossen Chu types. This range means the collection effectively documents the evolution of dotaku craftsmanship over several centuries of the Yayoi period.

Third, the remarkable number of same-mold relationships (dohan) discovered among the bells provides rare insight into ancient bronze-casting workshops. Of the 39 bells, 26 have been identified as belonging to 15 sets of same-mold pairs, and some of these matching bells have been found at sites scattered across western Japan — from Wakayama to Tottori to Hyogo prefectures — revealing the vast geographic networks of exchange and ritual that connected ancient communities.

Fourth, seven of the bells feature pictorial engravings of animals including deer, wild boar, sea turtles, soft-shelled turtles, and dragonflies. These images offer rare glimpses into the symbolic and spiritual world of the Yayoi people. Deer, in particular, are believed to have been revered as spirits of the land.

Finally, the proximity of the Kamo Iwakura Site to the Kojindani Site — just 3 kilometers away — where 358 bronze swords, 16 bronze halberds, and 6 additional bronze bells were discovered in 1984–1985, has fundamentally transformed scholarly understanding of the Izumo region's role in ancient Japan, suggesting it was a major center of political and religious power.

Highlights and What to Look For

Where to See the Bronze Bells

Surrounding Area and Nearby Attractions

The Kamo Iwakura Site sits within the broader landscape of ancient Izumo, a region extraordinarily rich in archaeological and cultural heritage.

The Kojindani Site, located just 3 km northwest across a mountain ridge, is where 358 bronze swords — also a National Treasure — were discovered in 1984. Together, the two sites form a remarkable pair that has reshaped our understanding of ancient Japan. The Kojindani Site Museum offers its own displays and walking paths.

Izumo Taisha Grand Shrine, one of Japan's oldest and most important Shinto shrines, is approximately 30 minutes by car from the Kamo Iwakura Site. According to mythology, the gods of all Japan gather here each autumn for their annual meeting.

The Kamo area itself is part of Unnan City, a region known for its cherry blossoms along the Hii River, traditional tatara ironmaking heritage, and scenic rural landscapes. Nearby, the Kisuki Line railway offers a picturesque journey through the mountains, and the Okuizumo area provides opportunities to learn about Japan's ancient iron smelting traditions.