The Hanashina Kofun Group is an important collection of ancient burial mounds scattered across present-day Chikuma City in Nagano Prefecture. Centered around four large keyhole-shaped burial mounds, known in Japanese as zenpō-kōen-fun, the group offers a fascinating glimpse into the political and social world of ancient Japan.
All four principal burial mounds are designated as National Historic Sites of Japan. Among them, Mori Shogunzuka Kofun and Ariyama Shogunzuka Kofun have been developed together with the Mori Shogunzuka Kofun Museum and the Nagano Prefectural Museum of History. The area is open to visitors as the Shinano no Sato History Park, making it an excellent destination for travelers interested in Japanese archaeology and early history.
Mori Shogunzuka Kofun was designated a National Historic Site in 1971. In 2007, three additional burial mounds—Ariyama Shogunzuka Kofun, Kurashina Shogunzuka Kofun, and Doguchi Shogunzuka Kofun—were added to the designation. Together, they are now protected as the Hanashina Kofun Group.
The surrounding area contains many other ancient burial mounds, including Saijoyama Kofun, also known as Zonjoyama Kofun, Sakayama Kofun, the Dohira Kofun Group, Sasazakiyama Kofun, and Kitayama Kofun. Most are believed to have been constructed between the late 4th and early 6th centuries.
Mori Shogunzuka Kofun is the largest of the Hanashina Kofun Group and one of the largest keyhole-shaped burial mounds in Nagano Prefecture. Located in the Mori district of Chikuma City, it stretches for approximately 100 meters along a ridge of Mount Ariyama.
The tomb is believed to have been constructed in the late 4th century, during the early Kofun period. Its position on a steep slope at an elevation of approximately 130 to 140 meters gives the mound an unusual shape. The rear circular section is elongated, and its central axis does not align perfectly with the front section.
The mound was originally covered with layers of stone, while three rows of haniwa clay figures surrounded it. At the top stood figurative haniwa depicting people and buildings, creating a striking ceremonial setting.
At the center of the summit, archaeologists discovered a large pit measuring approximately 15 meters long, 9.3 meters wide, and 2.8 meters deep. Inside it was a stone burial chamber of exceptional size, considered one of the largest of its type in eastern Japan.
The stone burial structure itself measures approximately 7.6 meters long, 2 meters wide, and 2.3 meters high. A full-scale reconstruction is displayed at the Mori Shogunzuka Kofun Museum, allowing visitors to appreciate the remarkable engineering involved in the construction of the tomb.
Much of the original burial chamber was disturbed by ancient grave robbing, but important artifacts have nevertheless been recovered. These include fragments of sankakubuchi-shinjūkyō bronze mirrors, haniwa, pottery, swords, iron arrowheads, and beads.
Some of these objects show connections with the Kinai region of central Japan, where the ancient Yamato polity was based. They provide valuable evidence of the political relationships that existed between powerful local leaders in Shinano and the emerging Yamato authority.
Archaeological investigations around Mori Shogunzuka Kofun have also uncovered 13 smaller circular burial mounds and approximately 100 additional burial structures, including haniwa coffins, stone coffins, and cylindrical coffins.
The presence of these later burials, continuing until around the 6th century, suggests that the site served as a burial ground for the ruling family and its descendants. Rather than representing the burial of a single individual, the site appears to have functioned as an important ancestral cemetery.
Following its designation as a National Historic Site in 1971, an extensive 11-year archaeological excavation and restoration project was carried out. The mound was reconstructed to closely reflect its appearance during the Kofun period.
Today, Mori Shogunzuka Kofun is open to the public and also serves as an educational resource. Its reconstructed appearance has even been introduced with photographs in Japanese elementary school textbooks, making it one of the best-known archaeological sites in the region.
Ariyama Shogunzuka Kofun is another keyhole-shaped burial mound built along the same ridge as Mori Shogunzuka Kofun. It is approximately 37 meters long and is thought to date from the end of the early Kofun period or the beginning of the middle Kofun period.
After archaeological investigation, the mound was reburied for preservation and is therefore not visible in its original form today.
Kurashina Shogunzuka Kofun measures approximately 83 meters in length, making it the third-largest keyhole-shaped burial mound in Nagano Prefecture.
It is believed to have been constructed during the middle Kofun period, later than Mori Shogunzuka Kofun. The mound is located at the end of a mountain trail next to the remains of Washio Castle. Its strategic location suggests that the site was later incorporated into a medieval fortification.
Doguchi Shogunzuka Kofun is approximately 67 meters long and is also believed to date from the middle Kofun period. It stands on a ridge near the border between Chikuma City and Nagano City.
Archaeological excavations were conducted jointly by the two cities from 1982 to 1986. Other burial structures have also been identified around the mound, revealing that the ridge was an important burial area over an extended period.
The Mori Shogunzuka Kofun Museum can be reached in approximately 25 minutes on foot from Yashiro Station on the Shinano Railway. By car, it is approximately 5 minutes from the Koshoku Interchange on the Nagano Expressway.
Visitors arriving by highway bus can also reach the museum in approximately 5 minutes on foot from the Yashiro bus stop on the Joshin-etsu Expressway.
From the Mori Shogunzuka Kofun Museum, the ancient burial mound can be reached in approximately 20 minutes on foot. A circulating bus provides a shorter ride of approximately 3 minutes.
The Hanashina Kofun Group provides valuable evidence for understanding the formation of ancient Shinano and its connections with the Yamato polity. Among the sites, Mori Shogunzuka Kofun stands out for its impressive scale, sophisticated construction, and important archaeological discoveries.
Walking through the restored burial mound and surrounding landscape offers travelers a rare opportunity to imagine the world of Japan more than 1,500 years ago. For visitors interested in archaeology, ancient history, and the origins of Japanese society, the Hanashina Kofun Group is a fascinating historical destination in Nagano Prefecture.