Kurotsuka-kofun Tumulus (an early keyhole-shaped mound in Tenri City, Nara Prefecture) (黒塚古墳)
Kurozuka-kofun (also known as Kurozuka-kofun) Tumulus is an early keyhole-shaped mound (about the end of third century) in Yanagimoto-cho, Tenri City, Nara Prefecture. It is famous as a site where 33 Sankaku Shinju-kyo Mirrors (triangular-rimmed mirrors decorated with gods and animals) were excavated.
Because the back circular part has three tiers and the front square part has two tiers, there is a big gap in height. There is a little arched bulge at the front of the front square part, from which shows that it is plectrum shaped. These are features of the early period tumulus. It has a shugo (moat around a tumulus).
Excavation Research and Afterwards
From 1997 to the next year the Kashihara Archaeological Institute, Nara Prefecture conducted the third excavation research and discovered 33 Sankaku Shinju-kyo Mirrors and one Gamontai Shinju-kyo Mirror (Mirror with figures of deities and sacred animals) in almost the same state when they were buried.
In the coffin the Gabuntai Shinju-kyo Mirror was placed near the head of the deceased person and one katana (one-edged sword) and one tsurugi (two-edged sword) on either side of it, and in the outside of the coffin 15 Sankaku Shinju-kyo Mirrors on the east wall and 17 on the west wall, which faced inward, were placed in the small space between the coffin and the wall. Swords, tetsuzoku (iron arrowheads), and kozane (small piece of iron or leather for armor) and unspecified iron goods were arranged. Neither gems nor arm adornments have been found.
The burial facilities of the back circular part is a pit stone chamber with its inside measurement approximately 8.3 meters in length, north small entrance 0.9 meters in width and about 1.7 meters in height, and the ceiling was built in a Gassho-zukuri style (an architect method with wooden beams combined to form a steep thatched roof that resembles two hands together) and corbelled out with flagstones from Mt. Kasuga and Mt. Shiba at the foot of Mt. Nijo. In the stone chamber a hollowed-out wooden coffin whose semi-circular cross section is more than 1 meter in full length was placed on the clay floor.
It seems that the center of the wooden coffin only in the 2.8 meters range was painted with cinnabar and the both ends were painted in red colcothar
The body is thought to have been placed in the cinnabar painted part. Moreover, this pit stone chamber points to almost true north, from which we can guess that the head of the deceased pointed to true north. This true north does not mean a simple coincidence, because it is thought that in the Yamato Dynasty there was probably a custom of burying the deceased with his or her head pointing to true north.
Tenri City not only manages the maintenance of this tumulus, now named Yanagimoto Park but also has set up, next to the tumulus, 'Tenri Municipal Kurozuka-kofun Museum' to exhibit a full-size model of a pit stone chamber. On January 29, 2001, it was designated as a national historic site.
Yanagimoto-jo Castle was built on the tumulus in the Sengoku Period (Period of Warring States), and Oda family built Yanagimoto Jinya (regional government office of the Yanagimoto Domain) in the site of the castle to be the government building of the Yanagimoto Domain in the Edo period.