The Kofun era and early state formationdifferentiation in social organization and speeds of social evolution during the Kofun period.
Most local societies during the period did not reach the level of early states. I would argue, rather,
that most local societies were at the tribal level, and that some of them were still at the chiefdom
level in the neo- evolutionary sense. Tambiah’s “galactic polity” model, therefore, more success-
fully accounts for the sharing of a keyhole shape for elite burial mounds and at the same time the
existence of autonomous local polities.
The early Kofun era
The presence of a central polity and clear social differentiation is evidenced by the difference in
the size and forms of mounded tombs. For example, in the Nara Basin, there was clear differenti-
ation in the size and shape of tumuli from the beginning of the Kofun era. Keyhole- shaped tombs
of more than 200 meters contrast with smaller keyhole- shaped tumuli of 100–150 meters, and
with circular mounded tombs less than 50 meters in diameter. Japanese archaeologists consider
these differences to have been a reflection of social status within the elite class because larger
quantities of bronze mirrors were deposited in larger keyhole- shaped mounded tombs.^22
For example, excavations of the 207-meter- long Sakurai- Chausu-yama tomb resulted in the
discovery of fragments from more than eighty bronze mirrors, including twenty- six sankakubuchi-
shinjū-kyō mirrors, nine Eastern Han Chinese mirrors, and ten Japanese mirrors modeled after
Chinese prototypes. Since this tomb has been heavily looted, it is likely that even more bronze
mirrors were initially deposited. This discovery suggests that even greater quantities of bronze
mirrors might be expected from contemporaneous tombs measuring over 250 meters. These
monumental keyhole- shaped tumuli, however, are designated as imperial mausoleums and are
consequently off- limits to excavation.
Located two miles north of Sakurai- Chausu-yama, in the southeastern Nara Basin, the Kuro-
zuka tomb measures 132 meters in length. From within the pit- style burial chamber, archaeolo-
gists discovered one Eastern Han Chinese bronze mirror inside the wooden coffin and thirty- three
sankakubuchi- shinju-kyo mirrors encircling the outside of the coffin. Since the burial chamber had
not been looted, the mirrors were discovered intact. These examples illustrate a strong correla-
tion between burial- mound size and the quantity of bronze mirrors deposited.
In addition to differences in size, tumuli shape is also believed to reflect differences in the social
status of the interred. The keyhole shape with a circular rear mound is thought to have been
reserved for the highest social status among the ruling class, while the square rear mound keyhole-
shape tombs contain occupants of the second highest social status. This interpretation is based on
the fact that the largest square rear mound keyhole- shaped tomb, the Nishiyama- zuka tumulus
(in the eastern Nara Basin), measures 180 meters—which, while of considerable size, is much
smaller than the largest keyhole- shaped tombs with round rear mounds. Four keyhole- shaped
tumuli with square rear mounds exist in the southeastern Nara Basin, which displays a great con-
centration of keyhole- shaped mounded tombs. They measure 145, 115, 110, and 90 meters in
length, belonging to the second tier, in terms of size hierarchy.
Circular- and square- mounded tombs measuring less than 50 meters in diameter or per side also
existed. In the southwestern Nara Basin, an undisturbed square- mounded tumulus dating to the
beginning of the fourth century was excavated. This tomb, Kamotsuba No. 1, measured only 20
meters per side and only four sankakubuchi- shinju-kyo mirrors were deposited with the dead. It is
also noteworthy that instead of a stone burial chamber, a wooden coffin was encased in clay; the
burial facility was very simple and its construction did not require a large investment of labor.
These examples in the Nara Basin are solid evidence for social stratification under a ruler
(Tsude’s first attribute). Since this three- tiered elite hierarchy represented by different tomb