Excavating the Mounded Tombs of the Kofun Period of the Japanese Archipelago: A History of Research and Methods

Abstract

During the approximately 350 years from the mid-3rdcentury AD to the 7th century AD, an enormous numberof mounded tombs were constructed across most of theJapanese archipelago. The period in which these moundedtombs, called kofun, were constructed is referred to inJapanese archaeology as the Kofun period. Built for the elite,these mounded tombs number approximately 160,000 andcan be found from southern Tōhoku to southern Kyūshū.Mounded tombs were built in a variety of sizes, fromgiant examples measuring almost 500m long to smallexamples measuring around ten meters. Mounded tombswere built in four main shapes: keyhole-shaped with around rear part, keyhole-shaped with a square rear part,round, and square. Of these, the keyhole-shaped tombswith round rear mound are the largest. Daisen in Ōsakaprefecture is the largest keyhole-shaped mounded tomb,its mound measuring 486m in length, 36m in height,and its total volume measuring approximately 1.4 millioncubic meters. Additionally, two moats fully encircle themound. According to the calculations made by ŌbayashiCorporation, a Japanese construction company, theconstruction of this mounded tomb would have requiredan aggregate work force of 6,807,000 laborers, assumingancient construction methods were used.