The longest sword in Japan and a large bronze mirror that is also unprecedented in the Japanese archaeological record have been unearthed at the Tomio Maruyama burial mound in Nara. The burial mound (known as a kofun) and artifacts date to the second half of the 4th century.
The sword is 2.37 meters (7’9″) long and 6 cm (2.34 inches) wide, more than twice as long as the previous record-holder that was found in a late 5th century burial mound in Hiroshima. It is the longest iron sword ever found in East Asia. The sword is a serpentine shape. Only 85 serpentine swords have been unearthed in Japan, and this is the oldest of them. It was hammered and bent in six places to create the characteristic wavy effect. Traces of organic remains from the sheath and grip wrapping were found on the pommel, hilt and scabbard. Its extraordinary dimensions and shape are a testament to the advanced ironworking techniques of the Kofun Period (ca. 250-538 A.D.).