Ebetsu Kofun Cluster

The Ebetsu Kofun Cluster (江別古墳群) is a group of Satsumon culture burial mounds in the Motoebetsu neighbourhood of the city of Ebetsu, Hokkaidō, Japan. Dating from the late eighth and early ninth century, and the northernmost kofun known to date, eighteen were jointly designated a National Historic Site in 1998.

Overview
The site is located at the northwest end of the Nopporo Hills that rise from the Ishikari Plain, at an altitude of 18 m, on the right bank of what was once the Seta Toyohira River, which empties into the Ishikari. First excavated in Shōwa 6 (1931) by Gotō Juichi, the term Gotō Site (後藤遺跡) is also used to refer not only to this series of "Hokkaidō-style kofun" (「北海道式古墳」), as he called them, but also to the nearby Jōmon and Zoku-Jōmon remains. The 1931 excavations uncovered sixteen burials, grave goods including blades (kenugigata-tō, warabite-tō, shō-tō, and tōsu), magatama, earrings, and earthernware spindle whorls. Subsequently, the burial mounds were indistinct.

In 1980 the site was investigated again. Of the burials previously excavated, other than for Mound 15, only the existence of the surrounding ditches could be confirmed, with all trace of the central arrangements for burial lost. In total, twenty-one burials were recorded, including those previously excavated; while Mounds 3, 4, and 5 have been lost to construction, the remaining eighteen have since been jointly designated an Historic Site. The surrounding ditches, with a depth of 50 cm or more, take the shape of a circle, oval, or horseshoe, and include large (8 - 10 m in diameter), medium (5 - 7 m), and small (up to 5 m) examples, those of a medium size being most numerous. As documented by the original excavator, the low circular burial mounds thereby enclosed had a diameter of 3 - 10 m and rose to a height of 0.3 - 1 m.

In the centre of Mound 15, 7 x and surrounded by a horseshoe-shaped ditch, is a shallow depression, 211 x and with a depth of 12 cm, which, from the impressions around the edges, appears to have been once occupied by a wooden casket. Artefacts recovered from the various surrounding ditches include Haji ware, Sue ware, iron arrowheads, plough tips, and earthen spindle whorls, and, from Mound 15, a red Sue ware cup with a pair of handles and a Haji ware vessel black inside, from the ditch, and from the central area, teeth, the remains of a skull, and an iron artefact that is perhaps part of the hilt of a warabite-tō. The circular ditch of Mound 1 is 10 m in diameter and 2 m deep; though disturbed and only the location of the mound is known, part of an iron sword was found from the central area, while an iron plough tip was found in the surrounding ditch.

Significance
Though the northernmost, those of the Ebetsu Kofun Cluster are not the only kofun in Hokkaidō - other examples include those at the Machimura Farm Site I (町村農場1遺跡), also in Ebetsu, Sapporo City K39 Site (札幌市K39遺跡) and a site in Kita-ku (北区北7条西6丁目) in Sapporo, Nishi-Shimamatsu V Site (西島松5遺跡) and Kashiwagi-Higashi Site (柏木東遺跡) (also known as the Moizari Kofun Cluster (茂漁古墳群) ) in Eniwa, Yukanboshi C15 Site (ユカンボシC15遺跡) and Yukanboshi C1 Site (ユカンボシC1遺跡) in Chitose, all eight sites in the Ishikari River System, and perhaps also the Kankan II Site in Biratori. Nevertheless, both in its form, and in the nature and origin of many of its grave goods, the cluster attests to cultural exchange with Honshū and the continuation and influence of the terminal-phase kofun known from Tōhoku well beyond the end of the Kofun period and into the age of the Ritsuryō national state, and at the time more locally of the Satsumon culture.