5
The Kofun era and early state
formation
Ken’ichi Sasaki
In the middle third century ce, giant keyhole- shaped (zenpō-kōen) mounded tombs, or kofun,
appeared in the southeastern Nara Basin, and quickly spread across most regions of Japan, except
for Hokkaido and the Ryūkyū Islands. The Hashihaka tumulus (278 meters in length, and 35
meters in height, with a circular rear mound 160 meters in diameter), located in Sakurai City, in
the southeastern part of the Nara Basin, is considered to be the earliest keyhole- shaped tomb.
This marks the beginning of the Kofun era, which lasted until the beginning of the seventh
century.
This flamboyant mortuary practice was not the only aspect of society that changed from the
Yayoi to Kofun eras. For one thing, the new age was also marked by the disappearance of moats
enclosing settlements. By the late Yayoi era in northern Kyushu, it seems that influential people
appeared, who could maintain larger storehouses, and yet these influential people resided within
moated enclosures together with ordinary residences.^1 In the Kofun era, settlements were no
longer enclosed by moats, but elites began to reside in mansions, enclosed by moats and spatially
distinct from ordinary settlements.^2 Archaeologists suspect that this radical change in settlement
patterns was related to the appearance of giant tumuli.
Scholars divided the 350-year- long Kofun era into three phases: Early (from the middle third
to the fourth century, ce), Middle (the fifth century), and Late (the sixth century). While the
principal symbol of authority in the Early phase was bronze mirrors, iron armor took over as the
most important status symbol in the Middle phase. The location of the largest keyhole- shaped
tombs shifted from the Nara Basin in the Early phase to the Osaka plain in the Middle phase. In
the sixth century, the location of the largest keyhole- shaped tumulus shifted back to the Nara
Basin, and horse trappings—saddles, stirrups, and other accoutrements of equestrian culture—
and decorative swords became the key status symbol. The construction of mounded tombs con-
tinued until the beginning of the eighth century, with kofun built in the seventh century sometimes
referred to as belonging to a Final Phase of tumulus construction. The seventh century is also
known as the historic Asuka Period.
The appearance of keyhole- shaped tombs in the middle third century was a major departure
from the mortuary practices of the preceding Yayoi period, which had been regionally distinc-
tive. The adoption of the keyhole- shape represented a replacement of localized customs with a
construction plan maintained by the highest- ranking chieftain in Yamato, and shared with local