The Mozu-Furuichi Kofungun, Ancient Tumulus Clusters, are groupings of monumental structures built with the large-scale aggregation of labor made possible by the political power of the ruling elites of Japan during the late 3rd to the end of the 6th century, the period of the formation of the ancient Japanese state. This property includes not only the Nintoku-tennô-ryô Kofun, the largest burial mound in the world, but also a variety of other kofun of different sizes, forms, and design, from the large rounded keyhole-shaped kofun to smaller round and square kofun.
As a result, the Mozu-Furuichi Kofungun, Ancient Tumulus Clusters, are an outstanding example, even among other tumulus clusters, that is both representative and typical in its reflection of the political and social of Japan in the period from the late 3rd century to the end of the 6th century.
The burial mound named “Ishibutai” is a combination of two Japanese words meaning stone (ishi) and stage (butai), and one explanation states that its name was derived from the sightings of foxes using the top of the burial mound as a dancing stage on full moon nights. The stones on the top of the tumulus are certainly large enough to serve as a performance stage.
The Ishibutai burial tumulus was first professionally excavated in 1933 and 1935. At that time the tumulus and moat surrounding the tumulus were excavated, but little was discovered, the tumulus having been pilfered by grave robbers throughout history. Currently Ishibutai has been designated as a Special Historic Site, and it is the largest megalithic structure in Japan. The kofun is a typical yokoana [side hole] style tomb with entrance being achieved from the south side. Once inside the tomb chamber, which can easily accommodate 20-30 people, one is instantly impressed with the size of the stones forming the walls and high ceiling. A burial mound of this magnitude obviously speaks for the political power of the leader of that time.
This kofun is located in Ikaruga, Nara Prefecture, Japan. It is estimated to date from the later half of the sixth century or the late seventh century. The burial mound is about 157 feet in diameter, 29.5 feet in height, and the stone chamber the mound covers is 52.49 feet in length. Excavation began in 1985. The tomb yielded gilt-bronze ornaments, horse trappings, and a stone coffin.
The tomb’s appearance is supplemented by the harness excavated in the tomb which is a Chinese product imported via the Korean Peninsula. Michio Maezono (Professor, Nara College of Arts) and Taichiro Shiraishi (Professor, Nara University) argue that it is highly possible Prince Anahobe (uncle of Prince Shōtoku, assassinated by Soga no Umako) and Prince Yakabe (prince of Emperor Senka) are the ones that were buried in this tumulus, because the tumulus was built when an assassination happened in June 587 according to “Nihonshoki” (Chronicles of Japan).
This stone tumulus dates from the Asuka Period [552-645] and is believed to be the tomb of a powerful member of the Soga clan, Soga no Umako, who, together with Shōtōku Taishi, was instrumental in establishing a foothold for Buddhism in Japan. Umako reportedly died in 626 and if this is indeed his tomb, then it most likely dates from that year.
Originally the megaliths were covered with earth, but over time the earth has eroded away leaving 30 large stones. It is reported that the huge stones used to build the tumulus, some weighing as much as 60 to 70 tons, came from as far away as Mt. Tōnomine, located approximately 1.86 miles away. Obviously, much effort was spent transporting the stones over that distance and placing them in formation. In the on-site building process, a hole was dug and stones placed standing up. Then earth was built up to the top of the standing stones, and other larges stones were moved over top of the earth, and placed on top of the standing stones. When all was in place, the supporting earth was removed leaving only the stones. This was a similar building practice used in the making of the Great Buddha of Tōdaiji in Nara.