Ōyasuba Kofun: A Kofun-Period Burial Mound Group in Japan
Site at a Glance
- Rating
- 4.2
- Popularity
- Very Low
- Country
- Japan
- Primary era
- Classical
- External website
- Open
- Eras represented
- Classical
- Civilizations
- Yamato
- Site type
- Burial
- Remains
- Necropolis
On this page7 sections
History
Ōyasuba Kofun is a group of five Kofun-period burial mounds in Japan, located in Tamuramachi, Kōriyama, Fukushima. The mounds were built from the latter part of the early Kofun period, an era conventionally dated from approximately the third to the sixth centuries when powerful leaders were buried in large earthen tombs, into the middle Kofun period. The group stands on the eastern side of the Abukuma River in the southern Tōhoku region and includes one front-square, rear-square mound and four circular mounds.
The main mound and regional connections
Ōyasuba No. 1 Kofun was probably built during the latter half of the fourth century. Its excavated objects and construction methods indicate a date in that period. It is the largest mound in the group and one of the largest burial mounds in the Abukuma River basin. It is currently regarded as the largest front-square, rear-square kofun in the Tōhoku region. This form has a rectangular front section joined to a larger square rear section.
The shape of No. 1 differs from the predominance of front-round, rear-square mounds in the Aizu region. Its form points to a relationship with the Nasu area of the former province of Shimotsuke, which covered parts of present-day Tochigi Prefecture and adjoining areas and had a concentration of front-square, rear-square burial mounds.
Later burials and preservation
The four circular mounds, provisionally dated to the latter half of the fifth century, are thought to have served as graves for a family living in a nearby settlement. Parts of these mounds were lost through residential development. The mounds were discovered in 1991, and the Kōriyama City Board of Education carried out archaeological excavations from fiscal years 1996 to 1998.
Ōyasuba No. 1, together with the other mounds, has been preserved and developed as Ōyasuba Historic Park. Ōyasuba No. 1 Kofun was designated a National Historic Site of Japan on September 6, 2000.
Remains
Setting and mound layout
The group occupies a low hill approximately 250 meters above sea level and about 15 meters above the surrounding plain. From this position, it overlooks the Asaka Basin. The Abukuma River flows from south to north along the eastern side of the site.
Ōyasuba No. 1 Kofun is a front-square, rear-square mound oriented with its front section toward the north. Its estimated overall length is approximately 83 meters, and its plan consists of two joined rectangular sections. The mound was formed partly by cutting down a pre-existing natural hill. The front section has two constructed tiers, while the rear section has three. Later modification affected the mound, and the summit of the rear section was substantially levelled.
The burial facility of No. 1
Numerous red-painted, pot-shaped vessels with holes pierced through their bases were recovered from the slope of the rear section. They were probably first placed on the summit. Immediately beneath the surface of the rear summit, a north-south burial facility contained a clay coffin bed approximately 10 meters long and 2 meters wide. Within it lay a split-bamboo-shaped wooden coffin measuring 9.2 meters in length.
Red pigment particles were scattered toward the northern part of the coffin. A bracelet-shaped stone object lay farther south, while traces of ritual activity were identified in the northern coffin area. The southern half contained one long sword, one sword, one spear, one sickle, and one flat iron axe. Other finds included pot-shaped pottery and a pointed iron scraper.
Burial objects and circular mounds
The bracelet-shaped stone object is made of green tuff and was probably deposited as a valued object. It is regarded as the first certain example of this kind of bracelet-shaped stone object found in the Tōhoku region. Some specialists classify it instead as a wheel stone because its body height, 1.6 centimeters, does not exceed its body width of 1.7 centimeters.
The wooden parts of the long sword’s scabbard and hilt survived in good condition. They had been wrapped with cloth approximately 2 centimeters wide and then hardened with resin. The surviving details provide evidence of the construction and treatment of the weapon placed in the burial.
Ōyasuba Nos. 2 to 5 are circular mounds, each approximately 15 meters in diameter. No. 2 contains a stone chamber made from stone slabs, while the other three mounds are not well preserved.
