Ebetsu Kofun Group

The Ebetsu Burial Mounds: Japan's Northernmost Ancient Tombs

On a low bluff above a former channel of the Toyohira River, near the northwestern edge of Hokkaido's Nopporo Hills, eighteen earthen mounds lie scattered across a grassy terrace in the Motoebetsu district of Ebetsu City. They are small, the largest barely waist-high today, and a visitor who did not know to look for them might walk past without noticing. Yet these low rises mark the northern boundary of an ancient burial custom, and they are the only ancient tombs still standing anywhere in Hokkaido.

The mounds were raised between the late 8th and the middle of the 9th century. That date matters, because it places them well outside the classic Kofun period (roughly the 3rd to 6th centuries), when great keyhole-shaped tombs were built across western and central Japan. Those earlier traditions never reached the far north. The Ebetsu tombs belong instead to a later, regional phenomenon: clusters of modest circular mounds that spread northward from the Tōhoku region during the early part of Hokkaido's Satsumon culture. Archaeologists often call them "terminal mounds," the last northern expression of the mound-building idea.

A Schoolteacher's Discovery

The site came to light in 1931, when a local elementary school teacher named Gotō Juichi recognized the mounds for what they were and recorded sixteen of them. For years afterward the place was known simply as the Gotō Site. A second scholar, the archaeologist Gotō Moriichi, later coined the term "Hokkaido-style kofun" for tombs of this kind, and the name stuck in academic writing.

A fuller picture emerged in 1980, when road construction prompted a thorough re-survey. Twenty-one mounds were confirmed. Three of them, numbers three through five, were destroyed by the work on the Ebetsu Interchange Line, but eighteen were preserved and form the protected site seen today.

By the time of these investigations the visible earth of most mounds had already worn away. Reconstructing their original form depends on the surrounding ditches and on Gotō's early reports. The tombs were low circular or slightly oval mounds, three to ten meters across and only about 0.3 to one meter high, each ringed by a shallow ditch. Some ditches form complete circles; others open at one end into a horseshoe shape. Researchers have sorted them by size into large (eight to ten meters), medium (five to seven), and small (under five).

What the Graves Held

Three mounds, numbers one, thirteen, and fifteen, preserved their central burial pits. Mound fifteen is the clearest. It measures roughly seven meters by five, with a horseshoe ditch around it. At its center lay a rectangular grave pit about 2.1 meters long and 0.7 meters wide, aligned northwest to southeast. Inside were traces of a wooden coffin, and in the southeastern corner the remains of teeth and a skull. Beside them lay an iron object believed to be part of the handle of a warabite-tō, a single-edged sword whose grip curls back like an unfurling fern frond, a weapon associated with the northern frontier.

Mound one, ten meters in diameter, was encircled by a ditch nearly two meters deep, though its burial chamber had been disturbed and only its position could be traced. The ditches across the site gave up a telling assortment of objects: cups of sue stoneware, some with paired handles; haji earthenware cups and jars, several blackened on the inside; iron arrowheads; an iron knife; the tip of an iron spade; and a clay spindle whorl. Gotō's first excavation had also turned up earrings and a magatama comma-shaped bead.

One detail does most of the historical work. The sue ware was not made locally. It was carried in from Honshu, and many of the iron pieces probably came the same way. The people buried here had real connections to the south.

Why the Site Was Designated

Tombs of this type, clusters of circular mounds about ten meters across, are well documented across the northern half of Tōhoku in the 7th through 9th centuries. In form, in the structure of their burial pits, and in their grave goods, the Ebetsu mounds match that northern Tōhoku tradition closely. They appear to have taken shape through sustained contact between the part of Tōhoku already under the control of Japan's centralized ritsuryō state and the regions beyond its direct reach, including Hokkaido.

Within Hokkaido, this kind of mound cluster was confined to the basin of the Ishikari River. Three such sites were once recorded there, but two have since been lost. Only the eighteen mounds at Ebetsu remain. That makes the site the single surviving marker of the custom's northern limit, and a rare physical record of how the far north and the ritsuryō world exchanged goods and ideas in the 8th and 9th centuries. On those grounds it was designated a National Historic Site on September 11, 1998.

Visiting the Site

The mounds sit at a busy road junction in Motoebetsu, and the entrance is genuinely easy to miss: a plain flight of steps beside an interpretive panel, with little to announce that something old and protected lies above. There is no parking at the tombs themselves. Drivers are asked to use the Ebetsu Recycle Bank car park, about a ten-minute walk away across the Setatoyohira River, a tributary of the Ishikari. From the Ebetsu-nishi interchange the site is roughly three kilometers east along the Ebetsu Interchange Line, about five minutes by car.

Public transport is awkward, and many visitors arrive by taxi from a nearby station. Timing rewards a little planning. The mounds read most clearly in early spring, just after the snow has melted, or in late autumn. By midsummer the grass grows tall enough to swallow the low profiles almost completely.

The grave goods recovered from the tombs are not kept at the site. They are held and displayed at the Ebetsu City Folk Museum (Kyōdo Shiryōkan) in the Midorimachi-nishi district, which is the better place to see the swords, pottery, and ironwork up close and to read the fuller story of the dig.