The Ogawadai Kofun Group is a cluster of ancient burial mounds located in Ogawadai, Yokoshibahikari Town, Sambu District, Chiba Prefecture. The site spreads across a tongue-shaped plateau on the eastern bank of the middle reaches of the Kuriyama River, in the central part of the Kujukuri coastal plain.
The group consists of five keyhole-shaped tombs (zenpo-koen-fun), 12 round burial mounds, and one square burial mound. Together, these ancient tombs provide valuable evidence of the history, society, and culture of the region during the Kofun period.
The Ogawadai Kofun Group contains burial mounds of various shapes and sizes. Among them, several tombs are particularly notable:
Kofun No. 6 is the largest mound in the group. Its apparent length is approximately 42 meters, although archaeological excavation has not yet been conducted there.
Archaeological excavations at the Ogawadai Kofun Group were carried out in 1974. Particularly important discoveries were made at Kofun No. 1 and Kofun No. 5, where numerous artifacts were recovered.
Three burial facilities inside Kofun No. 1 yielded a variety of artifacts, including:
These objects are valuable archaeological evidence for understanding the technology, material culture, and social conditions of the people who lived in the region during the Kofun period.
A wooden coffin found at the top of the rear circular section of Kofun No. 5 contained several important burial goods, including:
Excavations of the burial mound and surrounding moat also uncovered a wide variety of haniwa, clay figures and objects placed around ancient Japanese tombs. These included cylindrical haniwa, human figures, animal figures such as horses, deer, chickens, and waterfowl, as well as house-shaped haniwa.
The human-shaped haniwa from Kofun No. 5 include nine male figures and five female figures among those whose gender could be identified, for a total of 15 figures.
Examples include:
One particularly unusual feature is the design of the twin-legged figures. Rather than standing on a separate pedestal, their feet were formed to rest directly on the surface of the burial mound. Very few comparable examples are known, with one notable parallel being a sumo-wrestler figure from Harayama Kofun No. 1 in Izumizaki Village, Fukushima Prefecture.
These distinctive haniwa were designated as Tangible Cultural Properties of Yokoshibahikari Town in 2018.
Archaeological evidence suggests that different mounds within the Ogawadai Kofun Group were constructed during different periods:
Kofun No. 4 is particularly significant because it is clearly identified as a square burial mound from the final stage of the Kofun period.
The differences in dates indicate that the Ogawadai Kofun Group was not created all at once, but developed over a long period of time. The site therefore provides an opportunity to trace changes in burial customs and material culture across several centuries.
The Ogawadai Kofun Group is an important archaeological heritage site that preserves clues about the ancient history and culture of Yokoshibahikari. Its diverse burial mounds and rich collection of artifacts reveal aspects of the technology, society, customs, and beliefs of people who lived in the area more than a thousand years ago.
The variety of haniwa from Kofun No. 5 is especially valuable, offering a glimpse into how people, animals, buildings, and objects were represented in ancient Japan.
For travelers interested in Japanese archaeology, ancient history, and the Kofun period, the Ogawadai Kofun Group is a fascinating place to explore the ancient heritage of the Kujukuri region.