The Sengenyama tumulus is a zenpō-kōen-fun (前方後円墳), which is shaped like a keyhole, having one square end and one circular end, when viewed from above. It is situated on a plain to the southeast of the city center of Takasaki on the left bank of the Karasu River near the confluence of the Kabura River. The tumulus has a total length of 170.5 meters, with a posterior circular portion in three tiers and an anterior rectangular portion two tiers, and is orientated to the southeast. The surface was originally covered in fukiishi and both cylindrical haniwa and figurine haniwa (shaped as people and houses) have been recovered. In design, it closely resembles the Sakimisasagiyama Kofun in Nara, indicating a close connection with the Yamato kingdom. During the Meiji period, local inhabitants dug into the tumulus searching for the burial chamber, but discovered only vermillion painted fragments of stone and clay, and no grave goods. The chamber itself may have been a pit-shaped clay-lined hole.
The tumulus was surrounded by a double moat, with the inner moat having a width of 20 to 30 meters and the outer moat having a width of 56 to 65 meters.
Within the same Kuragano Kofun Cluster are a number of other very large keyhole-shaped tumuli, including the Ōtsurumaki Kofun (123 meters long), which has a separate National Historic Site designation, and the Kotsurumaki Kofun (87.5 meters).
Total length
171.5 meters
Anterior rectangular portion
66.3 meters long x 74.8 meters wide x 5.5 meters high, 2-tier
_zenkei-1.JPG)
