Noun
kofun (plural kofuns or kofun)
A megalithic tomb or tumulus in Japan, often with a distinctive keyhole-shaped mound.
Although the legend itself is not likely to be a historical fact, Aizu is rather close to southern Tōhoku, where the north end of keyhole kofun culture as of late 4th century is located. Source: Internet
Swords have been made from Kofun period and generally Japanese swords are the ones after the Heian period having curves, and there are many types of Japanese swords that differ by size, shape, field of application and method of manufacture. Source: Internet
Swords unearthed from some kofun tombs, such as the Inariyama Sword pictured at right, indicate his name was Waka Takeru (Ōkimi). Source: Internet
The earliest findings are from the Kofun period (3rd to 6th century). Source: Internet