Udotsuka Kofun is an ancient keyhole-shaped burial mound located in Kasugaoka, Heguri Town, Ikoma District, Nara Prefecture. It is believed to have been constructed around the middle of the 6th century, during the late Kofun period (approximately the 3rd to 7th centuries). Designated a National Historic Site of Japan, the tomb is an important archaeological monument, notable for its impressive scale, distinctive structure, and elaborate burial facilities.
Udotsuka Kofun stands on an isolated hill on the western bank of the Tatsuta River in Heguri Valley, at the eastern foothills of Mount Shigi in western Nara Prefecture. Its elevated position offers a glimpse into the landscape in which powerful local clans established their burial sites during ancient times.
An archaeological excavation conducted by the Nara Prefectural Board of Education in 1969 uncovered a variety of important structural features and artifacts, helping researchers better understand the tomb and the society that created it.
The mound has a single-tiered, keyhole-shaped design, consisting of a circular rear section and a rectangular front section. Its main axis runs north to south, with the rectangular front section facing north. At approximately 60.5 meters long, it is the largest burial mound in Heguri Valley.
Key dimensions:
Total length: 60.5 meters
Circular rear section: 35.3 meters in diameter and 6 meters high
Rectangular front section: 31 meters wide and approximately 6 meters high
No covering stones have been identified on the mound’s exterior, but rows of cylindrical haniwa clay figures were arranged along its surface. A surrounding moat approximately 2 meters wide has also been confirmed through archaeological investigation.
The main burial facility lies in the circular rear section and consists of a side-entry stone chamber with extensions on both sides of the entrance. Constructed from enormous stone blocks, the chamber opens toward the south and ranks among the largest examples of its kind in Nara Prefecture.
Overall chamber length: 14.2 meters
Main burial chamber: 6 meters long, 2.8 meters wide at the rear, and 4.3 meters high
Entrance passage: 8.2 meters long, 1.6 meters wide at the entrance, and 2 meters high
The side walls incline slightly inward as they rise, while the rear and front walls are built vertically. The stone materials are believed to have come from the area around Heguri Iwatoko Shrine, west of the tomb. A concealed drainage channel was also constructed beneath the entrance passage, demonstrating the builders’ attention to water management and structural durability.
Two stone coffins have been identified within the burial chamber and entrance passage. Their materials and construction techniques provide valuable evidence of the sophisticated stoneworking skills available during the late Kofun period.
Inside the main chamber is a composite stone coffin shaped like a traditional Japanese house. It was made from white tuff quarried from Mount Nijo. One side of the coffin body features a diagonal lattice pattern, adding a decorative element to the otherwise imposing stone structure.
A second composite stone coffin, also made from Mount Nijo tuff, lies in the entrance passage. Its lid is missing, and its base consists of three separate stone slabs. Together, the two coffins offer important clues about ancient burial customs and the craftsmanship of the people who built the tomb.
Excavations at Udotsuka Kofun have revealed numerous burial goods and haniwa figures. These discoveries shed light on the lives, beliefs, social status, and technological abilities of the people buried here.
Metal and personal objects: A mirror, small glass beads, earrings, an iron sword, iron spearheads, iron arrowheads, fragments of a wooden bow, small knives, an iron saw, and other iron tools.
Horse equipment: Gilt-bronze and iron horse fittings, reflecting the importance of horses and mounted warriors in ancient society.
Pottery: Sue ware, including lids, pedestal cups, spouted vessels, tall-necked jars with stands, and small jars, as well as Haji ware, including pedestal jars, tall cups, and small jars.
Haniwa figures: Figurative clay objects, including human-shaped and house-shaped figures, which may have served ritual or symbolic purposes around the burial mound.
These artifacts are preserved and exhibited at the Museum of Archaeology, Kashihara, affiliated with the Archaeological Institute of Kashihara, Nara Prefecture. They are valuable resources for understanding burial practices, material culture, and social organization during Japan’s Kofun period.
Recognized for its considerable historical and archaeological importance, Udotsuka Kofun was designated a National Historic Site on July 30, 1971. The findings of the excavation were published in 1972, and the site continues to be protected as an important part of the region’s cultural heritage.
The tomb is conveniently located approximately a five-minute walk from Tatsutagawa Station on the Kintetsu Ikoma Line. Visitors can combine a visit to this ancient burial site with a walk through the scenic Heguri Valley, where the natural landscape and archaeological remains together offer a sense of the area’s long history.
With its impressive stone chamber, carefully crafted coffins, and rich collection of burial goods, Udotsuka Kofun provides a fascinating window into the technology and beliefs of ancient Japan. It is an especially rewarding destination for visitors interested in archaeology, ancient burial mounds, and the history of Nara Prefecture.