Amenomiya Kofun Cluster: Kofun-Period Burial Mounds in Japan
Site at a Glance
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- Country
- Japan
- Primary era
- Classical
- External website
- Open
- Eras represented
- Classical
- Civilizations
- Yamato
- Site type
- Burial
- Remains
- Necropolis
On this page13 sections
History
The Amenomiya Kofun Cluster is a group of ancient Japanese burial mounds in Nakanoto, Japan, built during the Kofun period from the middle of the fourth century to the beginning of the fifth century. The Kofun period, broadly spanning the third through sixth centuries, was marked by increasingly centralized political authority, elite burials, and networks of influence across the Japanese archipelago. Centered on Mount Bijo in the central Noto Peninsula, the cluster occupies a mountain area whose principal tombs commanded views over Nanao Bay, the Mount Sekido range, the Ochi-gata tectonic depression, and the Sea of Japan.
Formation and sequence
The cluster is centered on Mount Bijo, a hill approximately 188 meters high. Municipal inventories count 36 tombs, while other descriptions give a total of about 40. The nearby Mori-no-miya and Nishibaba groups have sometimes been treated as related subgroups, but they are not included in the Amenomiya cluster considered here.
Tomb No. 1 belongs to the latter part of the early Kofun period. Tomb No. 17 predates it, a sequence indicated by the accumulated layers in the ditch beside Tomb No. 17. The mound produced no datable objects, but its position in the surrounding deposits establishes its earlier place in the cluster’s development. The construction order of Tombs No. 2, 7, 5, and 6 is also established, with No. 2 preceding No. 7, followed by No. 5 and then No. 6.
Tombs No. 1 and No. 2 have different forms but appear to follow a closely related design system. Their proportions, terraces, and level surfaces are notably similar. Tomb No. 2 has also been compared with large Kofun-period mounds near the Kinai region through proposed whole-number proportional relationships. Similar comparisons have been made with the paired circular and rectangular mounds at Odanaka in Nakanoto, across the Ochi-gata tectonic depression.
R36, also identified as Tomb No. 36 in Nakanoto and former Rokusei records, belongs to around the middle of the Middle Kofun period. Its characteristics have led to the possibility that it was a ritual installation rather than a burial mound. This later feature shows that activity at Mount Bijo extended beyond the period associated with the construction of the two principal tombs.
Beliefs and later history
Local tradition regarded the two principal tombs as the resting places of Ame-no-Hikage-hime, a deity associated with a pair of male and female divine turtles believed to lie hidden within the mountain. A shrine identified with Ame-no-Hikage-hime once stood on the front section of Tomb No. 1. The tenth-century Engishiki, a compilation of court regulations and ritual procedures, includes a shrine of this name in its register of shrine names, but the identification with the present shrine cannot be established. Another shrine with the same name stands in Ninomiya, Nakanoto.
A sumo ring formerly occupied the summit of the rear section of Tomb No. 1, where dedicatory matches were held. A commemorative inscription concerning the male and female divine turtles of Raigamine was dedicated in the nineteenth year of the Bunsei era. Written by a learned man from Koyo, it compares the mountain’s paired summits with male and female turtles and records prayers for rain and the prosperity of the region.
Modern investigations clarified the form and contents of the cluster. Tomb No. 1 was excavated in the 1990s, including a full examination of its mound surface and the first burial facility. Tomb No. 2 was examined during the same decade through eight trenches intended to establish the extent of its stone facing, while its burial facility remained unexcavated. Beginning in 1994, major improvements were undertaken through a national cultural-heritage utilization program. Fill was added over Tomb No. 1 to restore its approximate original mound height. The cluster became a National Historic Site in 1982. Thirty-five excavated objects held at the Furusato Soshukan became Ishikawa Prefecture tangible cultural properties in 2006, and the grave goods from Tomb No. 1 were collectively designated an Important Cultural Property of Japan in 2008. Part of Tomb No. 1 was damaged by the 2007 Noto earthquake.
Remains
The principal mounds
Tomb No. 1
Tomb No. 1 is a zenpo-koho-fun, a burial mound with two rectangular ends, positioned at the highest point of the cluster on Raigamine. Its surviving mound is 64 meters long. The rear section measures 43.6 meters across and rises 8.5 meters, while the front section is 31 meters wide. The summit carries the third-order triangulation point called Amemiyama, at an elevation of 187.95 meters.
Earlier reconstructions gave the mound a length of about 70 meters, and an aerial survey in 1991 produced a measurement of approximately 69 meters. Excavations beginning in 1992 defined the mound by the area covered with stone facing. Ground without facing was interpreted as a foundation platform or an external facility, which substantially changed the reconstructed length and shape, especially at the front. The mound was deliberately placed near the southeastern end of the ridge. Its builders cut into the natural ground and added soil in the valley areas, compacting alternating layers of two soils by a rammed-earth technique. Some of the fill contained weathered granite particles.
The faced part has two tiers and an almost level terrace around the mound. The facing stones were well preserved when excavated and were arranged in three main size groups. Stones 40 to 60 centimeters across formed the lower skirt, stones 20 to 30 centimeters across were used at the foot of the upper tier and in boundary rows, and stones of about 10 centimeters filled the spaces between them. Two irregularly circular rocks, each approximately one meter across, were set separately from the ordinary facing stones in the middle of the upper rear section, near the junction with the front section.
Gneiss makes up about 60 percent of the facing stone, followed by siliceous rock at 22 percent and granite at 15 percent. Pyroxene andesite accounts for about 1.6 percent, while limestone, pyroclastic rock, crystalline limestone, and dacite each account for less than 1 percent. Most of the stone probably came from gravels formed from Miocene conglomerate and pyroclastic formations around Mount Bijo. The pyroxene andesite appears to have come from beach boulders or bedrock in the Shika and Nadaura areas, and the dacite from the Anamizu Formation in northern Noto.
Burial facilities and grave goods
Two burial facilities were identified on the flat summit of the rear section. The earlier lay near the center, while the later lay to its west. The first burial pit was cut into a mound already raised to summit level. It measured 8.6 meters from north to south, more than 4.5 meters from east to west, and about 1.2 meters deep. Inside it was a clay-covered burial facility, meaning a coffin or chamber enclosed in compacted clay. The facility measured 7.2 meters long and 2 meters wide and contained a split-bamboo-shaped wooden coffin 6.2 meters long and 80 centimeters wide.
The coffin lay about 70 centimeters below the floor of the burial pit. Rope-fastening projections on both its lid and body suggest a deep coffin body and a comparatively thin lid. The distribution of grave goods indicates that the coffin interior was divided into three sections. The outer clay covering retains marks made by tamping, apparently with a log-shaped tool. A looters’ pit about 2.5 meters in diameter extended 1.8 meters below the pre-restoration summit and reached part of the coffin.
The second burial pit was larger, measuring more than 10 meters north to south and more than 4.5 meters east to west. Its upper layer was identified, while several trenches examined its interior. A wooden coffin placed directly in the ground is presumed. When the front section was levelled for construction of the former shrine, part of a stone burial chamber made from upright-stacked andesite slabs was exposed. This led to the proposal that another burial facility lay in the front section, although the 1990s excavations did not locate it.
The first coffin contained stone objects, weapons, agricultural tools, lacquered armor fittings, armor, shields, arrowheads, beads, a bronze mirror, and red pigment. The northern section held wheel-shaped stones, stone bracelets, swords, short swords, agricultural implements, and possible fragments of lacquered helmet and armor fittings. The central section contained a Japanese-made bronze mirror, wheel-shaped stones, stone bracelets, a koto-bridge-shaped stone object, tubular beads, and a sword. The southern section held swords, short swords, bronze and iron arrowheads, lacquered arrow shafts, a square-plated cuirass fastened with leather thongs, a hand-held shield, and a lump of cinnabar. Cinnabar is a red mineral pigment composed mainly of mercury sulfide.
Nineteen wheel-shaped stones and stone bracelets were recovered altogether, an unusually large quantity outside the Kinai region. The 52 bronze arrowheads all have willow-leaf forms. The nearly complete bronze mirror is 17 centimeters in diameter and carries a semicircular-and-square design band. A fragment of plain-weave silk adhered to part of its reflective surface, and a decayed wooden fragment lay beneath it. The mirror was positioned east of the buried person’s head. The square-plated, leather-thonged cuirass is an uncommon example from an early Kofun-period burial. Other grave goods included 165 metal artifacts, 34 jade beads, and fragments of lacquerware and pottery.
Pottery from the mound includes at least two double-rimmed jars from the western foot and the junction area of the rear section, a medium-sized straight-rimmed jar from the southern foot, four small round-bottomed bowls, one jar, one hand-moulded vessel, at least 15 dishes on pedestals, and seven jar bases. Most of the fragments were heavily worn. The mound’s form and objects place it in the latter part of the third or the beginning of the fourth phase of the early Kofun period. The bronze arrowheads chiefly correspond to phase three, the cuirass broadly spans phases three through four, and the pottery follows the Hokuriku Takabatake style before the Miyaji style. Comparable sequences place it around the Furu 3 or early Furu 4 phase in the Kinai region and the Matsukawado I phase in the Tokai region.
Tomb No. 2
Tomb No. 2 is a zenpo-koen-fun, a keyhole-shaped mound combining a rectangular front section with a circular rear section. It lies northeast of Tomb No. 1, with its front section facing that mound. Its summit is 4.5 meters lower than Tomb No. 1’s. The mound is 65.5 meters long, with a circular rear section 42 meters in diameter, a front end 28 meters wide, and a junction 25.5 meters wide.
Earlier measurements gave the mound a length of about 70 meters, while a 1991 aerial survey measured 72 to 74 meters. Later excavation revised the measurement by defining the mound through its stone-facing area, as at Tomb No. 1. Tomb No. 2 has two faced tiers and an almost level middle terrace around the mound. A third tier occurs on the front face. Skirt stones are clearly arranged around both the circular and rectangular sections, and the front face appears to use smaller stones than the circular section. The lower structure was not investigated, leaving its construction unknown.
The summit has a north-south burial facility thought to have been either a clay-covered chamber or a wooden coffin set directly in the ground. A dark layer found during preparatory excavation may represent soil produced by the subsidence of the burial facility, although its interpretation remains uncertain.
Other mounds and ridge features
Tomb No. 3
Tomb No. 3 is the largest circular mound on a narrow subsidiary ridge descending south from Tomb No. 1 toward the plain. It occupies a small summit where the ridge drops steeply. The mound has an orderly truncated-conical form with limited collapse, and a terrace cut into the natural ground surrounds its base. A shrine to Atago-no-kami was traditionally said to have stood on the summit.
Tombs No. 5, No. 6, and No. 7
Tombs No. 5, No. 6, and No. 7 stand close together at the eastern foot of Tomb No. 2. Their builders cut into the ridge and added fill, and each had a presumed wooden coffin placed directly in the ground. Tomb No. 5 contained a central burial facility 5 meters long and 1.5 meters wide on a north-south axis. Tomb No. 6 had a facility 4 meters long and 2.3 meters wide, aligned N50 degrees west. Tomb No. 7 had a facility 1.5 meters wide on the same axis, with a presumed split-bamboo-shaped coffin about 50 centimeters wide.
Tomb No. 5 had a level summit approximately 6 meters across. Tomb No. 6 used more fill than Tombs No. 5 and No. 7. Its mound was shaped on the west, north, and east sides, while its summit measured approximately 5 meters across.
Tomb No. 17
Tomb No. 17 lies on the narrow ridge extending southwest from Tomb No. 1, at a present elevation of 180.75 meters. Its irregularly circular mound apparently had a broad summit. It was formed by cutting into yellow, sandy natural ground known as Akaura sand and adding strongly compacted yellow-brown clayey fill containing weathered granite gravel.
A partial ditch runs along the eastern and southwestern sides of the mound. It measures 1.1 to 2.2 meters wide and 0.4 to 0.8 meters deep. An unexcavated stone burial chamber lies away from the mound center, while a square pit at the center has an undetermined function.
R36
R36 stands on a narrow ridge saddle. Its visible mound consists of a small amount of fill, with concentrations and rows of stones. The presumed wooden burial facility has an unknown form. Recovered objects include iron items, tubular beads, curved beads, and small disc beads. The feature’s shape and contents support its possible interpretation as a ritual installation rather than a tomb.
