The site is about ten minutes by car from Hayahoshi Station on the JR West Takayama Line.

Although the Senbōyama Site was probably chosen for defensive purposes, no traces of a moat or rampart have yet been found.

The Rokuji Kozuka Kofun (六治古塚墳墓) (2,490 square meters)is a rectangular "corner protruding" (Yosumi tosshutsugata funkyūbo) tumulus from the late Yayoi period.

It is located in the southern margin of a river terrace at an elevation of 57 meters near the Senbōyama Site and is believed to be contemporary with that settlement .

The presence of such a tomb at this location indicates as strong political and cultural connection with the San'in region, possibly the ancient Kingdom of Izumo.

It is presumed to be the tomb of the chief of the area, who lived at the Senbōyama site 270 meters northeast.

The Tomisaki Kofungun (富崎墳墓群) (8,118 square meters) is a cluster of three late Yayoi period rectangular "corner protruding" tombs (Yosumi tosshutsugata funkyūbo) located on the right bank of the Yamadagawa River on the northern margin of Tomisaki hill at an elevation of about 70 meters.

Mound No.9 is the only two conjoined-rectangle type tumulus in the group and is located at the highest elevation.

Haji ware pottery, including jars and cups of pedestals with traces of red pigment have been found.

It is presumed to be the tomb of the chief who ruled the Nei district, along with the Teshizuka tumulus, which is 400 meters south of the valley.

The Chokushizuka Kofun (勅使塚古墳) (27,651 square meters) is a large conjoined-rectangle style tumulus dating from the 3rd century.

It is presumed to be the tomb of the chief who ruled the Nei district, along with the Ōzuka Kofun, which is 400 meters north of the valley.