National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

The Tenjinyama Tumulus is part of the Yanagimoto Tumulus Cluster located on the eastern side of the Yamato Basin. It is a 113-meter-long, massive keyhole-shaped burial mound to the west of the alleged burial mound of the legendary Emperor Sujin. These bronze mirrors were found in and around a wooden chest in a pit-style stone burial chamber located at the center of the mound’s circular portion. The chest contained 41 kilograms of cinnabar lined with 20 mirrors with their reflective sides facing upward. Three mirrors were placed outside the chest as well. Other artifacts including iron swords, arrowheads, knives, and sickles were also found in and around the chest. The mirrors were placed clockwise along the chest’s edges, starting in the northerly direction and using 20 mirrors to go all the way around. Outside the chest, two mirrors were placed to the north and one mirror was placed to the south. The quantity and archaeological classification of each type of mirror is as follows:

・6 mirrors with TLV patterns
・4 mirrors with inward-facing petals
・4 mirrors with pictorial bands, gods, and divine beasts
・4 mirrors with beasts
・2 mirrors with legendary figures from ancient China
・2 triangular-rimmed mirrors with variant designs of gods and divine beasts
・1 mirror with figures, birds, and beasts

The Tenjinyama Tumulus has been dated by some archaeologists to the latter half of the 4th century. But the assemblage of grave goods feature an unusual combination of mirrors, primarily comprising mirrors from the Eastern Han dynasty (25–220 CE), like those with TLV patterns and linked arcs (“inward-facing petals”). The assemblage does not include any triangular-rimmed mirrors with gods and divine beasts, which are typically found in tumuli of the early Kofun period (ca. 3rd century–7th century). There is further no indication that human remains were ever interred in the Tenjinyama Tumulus, suggesting it was a satellite mound containing additional objects for the tumulus right to the east of it thought to entomb Emperor Sujin.