A wooden coffin unearthed from the Tomio Maruyama burial mound in Nara was presented to the media on February 6th. The coffin, which dates back to the late fourth century, was discovered in 2022 during the excavation of a protruding section of the tumulus.
The cylindrical coffin is remarkably well-preserved. It contains a 64-centimeter-long shield-shaped bronze mirror decorated with mythical creatures called “daryu” and a 237-centimeter-long serpentine sword, the largest of its kind found in East Asia.
Further investigation of the coffin began in December 2023. It revealed the coffin's construction, made by hollowing out a Japanese umbrella pine log measuring over 5.3 meters in length and 64 to 70 centimeters in diameter. The coffin was placed at the bottom of a rectangular pit, approximately 7.4 meters long and 3 meters wide, which was dug into the protruding part of the burial mound. Blocks of clay were stacked around the coffin and encased in further clay.
Around one-third of the lid, along with a rope-holding protrusion believed to have been used during transport, still remains. End caps fitted inside the coffin were used to seal the ends.
The remarkable preservation of such a large portion of the coffin after approximately 1,600 years is exceptional, as wooden coffins typically decay and disappear in the soil over time.
The Nara Board of Education plans to investigate the coffin's interior further. Metal detector readings suggest the presence of iron-made grave items, such as weapons or agricultural tools, which will be announced around mid-March.