Excavated Items from Chasuriyama Tomb, Hyogo Prefecture

Artifacts from Chasuriyama Kofun: Treasures of an Ancient Tajima Chieftain

Deep in the mountainous terrain of Asago City, Hyogo Prefecture, lies one of the most significant archaeological discoveries of early 21st-century Japan. The artifacts unearthed from Chasuriyama Kofun — a massive circular burial mound dating to the first half of the 5th century — provide an extraordinary window into the power, craftsmanship, and political networks of Japan's Kofun period. Designated as a national Important Cultural Property in 2013, this remarkable collection of 664 items includes armor, weapons, bronze mirrors, jade ornaments, and haniwa clay figures that together tell the story of a regional chieftain with deep ties to the Yamato court.

Historical Background

Chasuriyama Kofun is situated on a ridge overlooking the Wadayama Basin at an elevation of approximately 144 meters, along the Hoju Pass that connects the western Wadayama Basin with the eastern Santo Basin. The tomb was constructed in the early 5th century during the Middle Kofun period, a time when the Tajima region (present-day northern Hyogo Prefecture) was home to a succession of powerful local chieftains.

The Wadayama and Santo basins contain over 1,400 ancient burial mounds, reflecting the region's importance as a political center. Chasuriyama Kofun succeeded the Ikeda Kofun — a 141-meter keyhole-shaped tomb that was the largest Middle Kofun period tomb on the Sea of Japan side — as the principal chieftain's burial. The tomb was discovered in 2001 during construction of the Kita-Kinki Toyooka Expressway, prompting the road's route to be altered to preserve the site. Full-scale excavation by the Hyogo Prefectural Board of Education between 2000 and 2002 revealed an undisturbed burial with an astonishing wealth of grave goods.

Why These Artifacts Were Designated as an Important Cultural Property

The collection was designated a national Important Cultural Property on June 19, 2013, for several compelling reasons. The 664 artifacts represent a complete and undisturbed assemblage from two burial chambers, offering an unparalleled snapshot of Kofun-period funerary practices. The quality and variety of the grave goods rival those found in the great tombs of the Kinai region (the ancient heartland around Nara and Osaka), yet the burial methods retain distinct local Tajima traditions — creating a uniquely informative combination.

Of particular significance is the triangular-plate leather-laced collar-attached short armor (sankakuita kawatoji eritsuki tanko), which was the first example ever found outside the Kinai region. This type of armor is believed to have been bestowed directly by the Yamato court, indicating the buried chieftain's exceptionally high status. The collection is invaluable for understanding the relationship between the central Yamato government and regional chieftains, Kofun-period ritual practices, and the state of metalworking and craft technology in 5th-century Japan.

Highlights of the Collection

Armor and Helmets

The first burial chamber contained two complete sets of armor and helmets. One set pairs the rare collar-attached short armor with a triangular-plate leather-laced visor-attached helmet. The second set comprises a rectangular-plate leather-laced short armor accompanied by neck guards, shoulder guards, and a vertically-joined riveted visor-attached helmet — an important early example of the riveting technique being introduced into Japanese armor construction. These armor sets demonstrate that the buried chieftain was a formidable warrior.

Bronze Mirrors

Four bronze mirrors were recovered from the two burial chambers — three from the first and one from the second. Among them is a banryukyo (coiled dragon mirror), a prestigious item thought to have been gifted by the Yamato court. The mirror from the second chamber is a domestically produced beast-band mirror measuring 14.8 centimeters in diameter.

Weapons

A vast arsenal of weapons was found, including 85 iron swords, daggers, and spears, along with approximately 400 iron arrowheads that were originally bundled as quivers. Notable among these is a ring-pommel sword (sokantou tachi), a type with Korean Peninsula origins that is extremely rare in Japanese burial contexts. An iron-handled adze (tetsu-e tsuki chouna), also of Korean derivation, further highlights the international connections of the Tajima chieftain.

Jade and Ornaments

Over 2,000 pieces of jade and other ornamental stones were recovered, including magatama (curved beads) and tubular beads. In the second burial chamber, a necklace arrangement of magatama and kudatama was found positioned around the deceased's neck, preserving the original wearing arrangement.

Haniwa Clay Figures

Twelve haniwa are included in the designated collection, featuring cylindrical haniwa, morning-glory-shaped haniwa, a large house-shaped haniwa with a hip-and-gable roof (irimoya-zukuri), and a rare ceremonial fan-shaped haniwa (sashiba-gata). The house-shaped haniwa was placed directly atop the first burial chamber, offering insight into Kofun-period funerary rituals.

Lacquerware Remains

Seventeen fragments of lacquered items, including shield remnants, were preserved in remarkably good condition. The excellent state of lacquer preservation on the weapons and shields is considered outstanding even by national standards.

The Kofun Itself

Chasuriyama Kofun is a two-tiered circular burial mound measuring approximately 90 meters in diameter and 18 meters in height, making it one of the largest circular tombs in the Kinki region. The summit features an unusually broad elliptical platform measuring 36 meters east-west by 30 meters north-south. Two burial chambers were carved into the summit — the larger first chamber held a composite box-shaped wooden coffin 8.7 meters long, divided into four compartments for the body and grave goods, while the smaller second chamber contained a 4.8-meter coffin divided into three sections.

While the grave goods clearly indicate strong ties to the Yamato court, the burial methods reflect distinct Tajima regional traditions: the use of a multi-compartment wooden coffin, the practice of laying the body head-to-the-east on a gravel bed, and the use of local hillside stones rather than river pebbles for the slope covering. This blend of central prestige goods and local funerary customs makes Chasuriyama a key site for understanding center-periphery relations in Kofun-period Japan. The tomb was designated a National Historic Site in 2004.

Visitor Information

The artifacts from Chasuriyama Kofun are housed and displayed at the Asago City Archaeological Center, known as Kodai Asago-kan (Ancient Asago Hall). This free-admission museum is located adjacent to the Tajima no Mahoroba roadside station, making it convenient for travelers. The museum features hands-on activities including magatama bead-making workshops. Nearby, the Chasuriyama Kofun Study Hall at the base of the tomb itself offers video and panel exhibitions explaining the site, also free of charge.

The tomb has been preserved as Chasuriyama Kofun Park, where visitors can climb to the summit and appreciate the impressive scale of this ancient monument while enjoying panoramic views of the Wadayama Basin. The site is accessible by car from the Kita-Kinki Toyooka Expressway or by JR train to Wadayama Station.

Surrounding Attractions

Asago City is rich in historical and natural attractions. The famous Takeda Castle Ruins, often called the "Castle in the Sky" for its spectacular cloud-sea views, sit atop a nearby mountain. The Ikeda Kofun, a massive 141-meter keyhole-shaped tomb and the largest Middle Kofun period tomb on the Sea of Japan coast, is also in the area. The Ikuno Silver Mine, part of a nationally designated Important Cultural Landscape, offers underground tours of historic mining tunnels. For nature lovers, the surrounding mountains provide excellent hiking, and the area is home to populations of the Special Natural Monument giant salamander (Ōsanshōuo). The roadside station Tajima no Mahoroba adjacent to the museum offers local produce and regional cuisine.