Shimanoyama Kofun is a large keyhole-shaped burial mound located in Tōin, Kawanishi Town, Shiki District, Nara Prefecture. It is an important archaeological site that preserves evidence of the ancient Yamato region, one of the political and cultural centers of early Japan. The mound is designated as a National Historic Site, and numerous artifacts excavated from it have been designated as Important Cultural Properties of Japan.
The tomb forms part of the northern group of the Umami Kofun Group and is also associated with the broader cluster of ancient burial mounds known as the Miyake Kofun Group. Its impressive scale, distinctive construction, and rich collection of burial goods provide valuable insights into the society, beliefs, and craftsmanship of the Kofun period, which lasted approximately from the 3rd to the 6th centuries.
Shimanoyama Kofun lies approximately one kilometer east of Kawai Ōtsukayama Kofun. It was constructed on a slight rise on the left bank of the Teragawa River. The site is also locally known as Shimaneyama Kofun.
The mound measures approximately 195 meters in length and 175 meters at its maximum width, according to the commonly cited measurements of the burial mound. It is surrounded by a moat with a shield-like outline, adding to the scale of the overall complex. Projections known as tsukuridashi extend from the eastern and western sides near the junctions between the front and rear sections. These features are characteristic of some large Kofun-period tombs and may have served ceremonial functions.
Note that published measurements can vary depending on whether the mound itself or its surrounding features are included. The site’s overall dimensions reflect the considerable resources required to construct such a monumental tomb.
Excavations have revealed paving stones known as fukiishi on the mound’s surface, along with clay figures called haniwa. These include cylindrical figures with flared, morning-glory-shaped rims, as well as representations of houses, shields, and quivers. Such objects were placed around burial mounds and are important evidence of the ceremonial practices and material culture of the Kofun period.
One particularly noteworthy discovery was made during an excavation in 2005, when a plant-fiber basket was unearthed near the western junction of the mound’s front and rear sections. Researchers believe it may have been used in rituals associated with the tomb. Its preservation offers a rare opportunity to investigate the ritual practices and spiritual life of people in ancient Japan.
The location of Shimanoyama Kofun is significant because it lies in an area where major waterways of the Yamato Basin converge. In ancient times, rivers served as important routes for transporting people and goods, connecting settlements and facilitating the movement of resources.
Kawai Ōtsukayama Kofun, located nearby, occupies a similarly important position. The two tombs also share similarities in their overall shape, suggesting that their builders may have been connected through political relationships, regional alliances, or shared traditions. Although the precise relationship remains uncertain, their locations and architectural features provide valuable clues about the organization of power in ancient Yamato.
A vertical stone burial chamber, known as a tateana-shiki sekishitsu, has been identified in the center of the rear section of the mound. Some of its ceiling stones have survived around the burial mound. These stones were made from Tatsuyama stone, a type of stone quarried in Hyōgo Prefecture and used in ancient Japanese construction.
The tomb was robbed in the past, and many of its original burial goods were lost. Some objects associated with the site are reported to have entered overseas museum collections, reflecting the complicated history of archaeological discoveries and the dispersal of cultural artifacts.
An archaeological investigation in 1996 uncovered a burial facility known as a nendokaku, or clay-coated burial chamber, at the top of the mound’s front section. The burial pit measured approximately 10.5 meters from east to west and 3.4 meters from north to south. Within it was a clay structure measuring about 8.5 meters long and between 1.7 and 2 meters wide.
Approximately 2,500 artifacts were recovered from outside the coffin. These included magatama comma-shaped beads, small stone beads, tubular beads, and stone objects shaped like the bridges of traditional Japanese stringed instruments. The large quantity and variety of these objects reveal the elaborate burial customs practiced by the region’s elite.
Other finds associated with the clay layer surrounding the coffin included approximately 80 wheel-shaped stone ornaments, 21 stone objects known as kuwagata-ishi, 32 stone bracelets called ishikushiro, and five small iron knives.
Objects recovered from inside the coffin included three containers made of jasper, three bronze mirrors, five large tubular beads, 11 combs, and ornaments for necklaces and wrists. The quantity and types of jewelry and personal ornaments have led researchers to suggest that the individual buried here may have been a woman. This remains an archaeological interpretation based on the burial goods rather than a definitive identification.
In 1998, artifacts excavated from Shimanoyama Kofun were designated as Important Cultural Properties of Japan. They are significant for the information they provide about funerary rituals, decorative arts, metalworking, and the exchange of materials and ideas during the Kofun period.
Animal-design mirrors: Three bronze mirrors that offer insight into the decorative traditions and cultural connections of ancient Japan.
Large jasper tubular beads: Five substantial beads, part of a wider collection of ornaments associated with elite burials.
Jasper and other stone beads: Numerous tubular beads, slender beads, and rounded beads that demonstrate the importance of personal adornment.
Stone beads and ornaments: A collection of ornaments made from talc and other stone materials, reflecting the variety of materials used in burial rituals.
Iron knives and small blades: A group of iron implements that provides evidence of metalworking and the objects placed in elite tombs.
Ishikushiro stone bracelets: Approximately 31 to 32 examples are recorded in different artifact inventories, illustrating the significance of stone ornaments in ancient funerary customs.
Wheel-shaped stone ornaments: Approximately 80 to 81 pieces are reported in the excavation records and artifact listings.
Kuwagata-ishi: Twenty-one distinctive stone ornaments whose shape resembles the antlers or pincers suggested by their Japanese name.
Koto-ji-shaped stone object: An artifact resembling the bridge of a traditional Japanese stringed instrument.
Stone containers: Three small containers made from stone, demonstrating the variety of objects included in the burial assemblage.
Many of the artifacts from Shimanoyama Kofun are preserved and displayed at the Museum of the Archaeological Institute of Kashihara, Nara Prefecture. Some related materials may also be exhibited at Tenri University Sankōkan Museum.
Seeing these objects in person helps visitors appreciate the technical skill required to produce finely worked ornaments and the importance of decorative objects in the funerary traditions of ancient Japan. The artifacts also provide a closer look at the social status and cultural connections of the people buried in the region’s monumental tombs.
Shimanoyama Kofun is an important resource for understanding the Kofun period, particularly the development of burial rituals, religious practices, and political authority in the Yamato region. Its monumental scale reflects the power of the community responsible for its construction, while the artifacts discovered inside reveal sophisticated craftsmanship and a rich tradition of personal ornamentation.
The discovery of the plant-fiber basket and the extensive collection of stone and metal objects adds further depth to our understanding of ancient Japanese society. Together with nearby burial mounds, Shimanoyama Kofun helps researchers reconstruct the relationships between powerful families, the movement of goods along waterways, and the emergence of early political centers.
For travelers exploring Nara Prefecture, the site offers a connection to a period long before the great temples and capitals for which the region is famous. Although the mound itself is primarily an archaeological landscape rather than a conventional sightseeing attraction, it provides a compelling opportunity to reflect on the people, beliefs, and achievements that shaped ancient Yamato.