Furumiya Kofun: A Square Burial Mound of Japan’s Asuka Period
Site at a Glance
- Rating
- 4
- Popularity
- Very Low
- Country
- Japan
- Primary era
- Medieval
- External website
- Open
- Eras represented
- Medieval
- Civilizations
- Yamato
- Site type
- Burial
- Remains
- Burial Mound
On this page9 sections
History
Construction in the Asuka Period
Furumiya Kofun is a square burial mound in Ōita City, Japan, built during the middle to latter part of the seventh century in the Asuka period. It belongs to the terminal Kofun period, Japan’s ancient mound-building era, and its square form is known as a hofun. The tomb was constructed on the southern slope of a low hill beside a small valley formed by the Bishamon River. The river lies to the south, while mountains rise behind the mound, a setting interpreted as reflecting the influence of feng shui principles.
The tomb’s burial chamber follows a Kinai style associated with the political centers of central Japan around modern Nara and Osaka. Its use in Kyushu is unique and points to a strong connection with the central government. The construction of the mound after the 646 Taika-era Edict on Thin Burials, together with its scale, is consistent with the grave of a high-ranking official.
The Proposed Burial
The person buried at Furumiya Kofun is unknown. A leading hypothesis identifies the occupant as Ōita no Kimi Esaka, a member of the Ōita no Kimi clan, an ancient lineage active in the Ōita River basin. Esaka served Prince Ōama, later Emperor Tenmu, during the Jinshin War, a succession conflict in 672 in which Ōama defeated the forces supporting Prince Ōtomo.
On 24 June 672, Esaka was sent to request bells from relay stations. He later went to the Omi region and escaped with Prince Ōtsu on 26 June before joining Ōama’s forces in Ise. Esaka died in June 675 and received the outer Lesser Purple rank, approximately equivalent to the junior third court rank. That rank corresponded to the class of official for whom a mound of this scale was prescribed.
Another possible occupant is Esaka’s kinsman Ōita no Kimi Wakami, who also served on Tenmu’s side during the Jinshin War. Wakami later fought under Murakuni no Muraji Oyori, taking part in the campaign from Fuwa into Omi and leading the attack that defeated Prince Ōtomo’s forces at the Battle of Seta on 22 July 672. He died in March 679 and received the outer Lesser Brocade Upper rank, approximately equivalent to the fifth court rank. Esaka is considered the more probable candidate, but the identification remains uncertain because no object naming the deceased has been found.
Rediscovery and Conservation
Furumiya Kofun was reported in 1925 and drew renewed attention during a 1979 survey of land intended for housing development. The Ōita City Board of Education excavated the site in 1980 and 1981, followed by further investigations connected with improvements to the site. Those later investigations were summarized in 1993 and fully reported in 1996.
The tumulus became a National Historic Site of Japan on 11 May 1983. It was subsequently developed as a historic-site park, while entry into the stone burial chamber remained restricted. Conservation work was completed in March 1996.
Remains
Mound and Burial Facility
Square Mound
The mound is approximately 12.5 meters from north to south and 12 meters from east to west, with another recorded measurement of about 12.45 by 12.15 meters. Its southern front reaches approximately 4.9 meters in height. Because it was built on a slope, its appearance changes when viewed from the front and sides.
Construction began by hollowing a semicircular depression into the hillside. The mound was then raised with alternating layers of gravelly sandy soil and clay-rich soil. The excavated structure provides no evidence of rammed-earth construction or a stone revetment.
Side-Entrance Stone Chamber
The burial facility is a side-entrance stone chamber, also described as a stone-coffin-style chamber, opening toward the southeast. Its main block was formed by hollowing a rectangular block of tuff, a relatively soft volcanic rock. The block measures approximately 2.50 meters long, 1.65 meters wide, and 1.77 meters high. Inside, the chamber is about 2.16 meters long, 0.81 meters wide, and 0.88 meters high.
Chisel-like tool marks remain on the chamber walls. The ceiling has a slightly barrel-shaped curve, and a socket about four centimeters wide was cut into the front for fitting a blocking stone. A passage made from cut tuff stones extends from the chamber. It is approximately 2.7 meters long, 1.1 meters wide, and 1.2 meters high, with two side-wall slabs and one ceiling stone shaped to fit between them.
Recovered Pottery
The burial chamber had been open since antiquity, leaving its grave goods poorly known. Excavation recovered small fragments of Sue ware, a high-fired gray pottery produced in ancient Japan. These included one cup lid and one foot from a tall-stemmed cup. The fragments date to the middle or latter part of the seventh century, although it remains uncertain whether every piece originally belonged to Furumiya Kofun. Medieval earthenware fragments were also recovered.
