Location and Overview
Akabori Chausuyama Kofun was constructed on the summit of an eastern ridge of the Tadayama Hills in eastern Gunma. Its elevated position offers wide views over the surrounding landscape and is thought to reflect the authority and status of the powerful local leader buried here.
In 1929, a full-scale archaeological excavation was carried out by the Imperial Museum. The site is particularly significant because it was the first kofun in Gunma Prefecture to undergo a formal archaeological investigation.
A Keyhole-Shaped Burial Mound
The mound has a distinctive scallop-shell-shaped design, a variation of the traditional keyhole-shaped kofun. Its front section is relatively short, creating a shape similar to a scallop shell when viewed from above.
The main axis of the mound runs perpendicular to the ridge, with the front section facing west. The burial mound was constructed in two levels, and its surface was covered with stones known as fukiishi, made from split stones and river stones.
A surrounding moat was also constructed around much of the mound. Interestingly, no moat has been identified on the eastern side of the rear mound, suggesting that the builders made effective use of the natural terrain when designing the site.
Burial Chambers and Grave Goods
Two wood-and-charcoal burial chambers were identified beneath the summit of the rear circular section of the mound.
Excavations uncovered a remarkable variety of grave goods, including bronze mirrors such as the Rokushinzo Mirror and an Inner Floral Design Mirror. Weapons including swords, blades, and spears were also discovered, together with iron axes, armor, helmets, iron arrowheads, and stone replicas of everyday objects.
The quantity and quality of these objects indicate that the individual or individuals buried here held a high political and military status within the society of ancient Gunma.
Remarkable Haniwa Clay Figures
One of the most important features of Akabori Chausuyama Kofun is its extraordinary collection of figurative haniwa, particularly the house-shaped examples.
House-Shaped Haniwa
The excavated house-shaped haniwa include models with gabled roofs and hipped roofs, as well as representations of storehouses and sheds. These miniature buildings offer valuable information about the architecture and living environment of elite communities during the Kofun period.
Other forms of haniwa found at the site include figures representing fenced enclosures, armor, protective leg coverings, stools, offering stands, and chickens.
Paired Rooster and Hen Figures
The chicken-shaped haniwa are especially interesting because they are thought to have been made as a male and female pair. These artifacts are also important for understanding the relationship between the kofun and the specialized workshops that produced haniwa.
Together, the haniwa provide a vivid glimpse into the beliefs, architecture, rituals, and social structure of the Kofun period.
Dating and Historical Significance
Akabori Chausuyama Kofun is generally thought to have been constructed during the middle of the 5th century, probably from around the middle to latter part of the 5th century.
Its importance extends beyond the size and design of the mound itself. Because it was the first kofun in Gunma to receive a full academic archaeological investigation, the site has played an important role in the development of kofun archaeology in the prefecture.
The discoveries also provide unusually detailed evidence about the arrangement of haniwa and the nature of elite residential and ceremonial spaces during the Kofun period.
Historic Site Designation and Related Museums
The kofun area received historic-site protection in 2004 and is now preserved as an Important Historic Site designated by Isesaki City.
Some of the artifacts discovered during excavations are preserved and displayed at institutions including the Tokyo National Museum and the Akabori History and Folklore Museum. Visiting these collections can provide additional context for understanding the archaeological discoveries from the mound.
Why Visit Akabori Chausuyama Kofun?
Akabori Chausuyama Kofun is a quiet historic site where visitors can explore the political, cultural, and everyday life of ancient Japan through archaeology.
Although it stands in a peaceful hilly landscape rather than in a major tourist district, the site preserves important evidence of the powerful communities that lived in the Gunma region approximately 1,500 years ago.
Several other ancient burial mounds and historical facilities can also be found in the surrounding area, making the site a worthwhile destination for travelers interested in Japanese archaeology, ancient history, haniwa, and the Kofun period.
Walking around the mound and imagining the people who built this monumental tomb offers a fascinating way to connect with the distant past of Gunma and discover a lesser-known side of Japan’s ancient heritage.