This study examines the political nature of the group that built the wooden chamber tombs around Oksung-ri in Heunghae by analyzing tomb structure, grave goods, grave goods distribution pattern, and the location of the tombs within the landscape (referred to collectively as ‘tomb aspect’). The ‘tomb aspect’ of the Oksung-ri tombs can be categorized into 3 phases. In Phase 1, dating from the mid 2nd century to the second quarter of the 3rd century, the A1 type wooden chamber tomb appeared and a large number of iron weapons were buried as grave goods. Phase 1 is the stage that witnessed the growth of the Oksung-ri political group. The Saro-guk polity supported this group for protection from invasion by Wa and Mohe, which provided the background for the growth of the Oksung-ri political group.
In Phase 2, dating from the third quarter of the 3rd century to the first quarter of the 4th century, E·F type wooden chamber tombs came to replace the A1 type wooden chamber tomb, and traditional grave goods, such as the pedestal jar with a wide rim and brazier-shaped pottery, came to be replaced by the Gyeongju style brazier-shaped pottery stand, jar with two lugs, iron armour with long vertical plates, jade comma-shaped bead, and bracken-shaped iron spearhead. In addition, change could also be observed in terms of burial precinct. The existing burial ground at Oksung-ri continued to be maintained, but at the same time, new burial grounds came to be formed at Namsung-ri and Masan-ri. Of these, the Namsung-ri burial ground represented the central burial precinct. Each of the burial grounds featured large-sized wooden chamber tombs. These Phase 2 ‘tomb aspects’ are seen to be associated with the growth of the Saro-guk polity. In Phase 3, dating to the second quarter of the 4th century and beyond, large-sized wooden chamber tombs were built in the early part of this phase but then disappeared. In addition, the construction of tombs at high locations within the Oksung-ri burial ground came to an end, and the spread of Early Silla style pottery spread could be observed. The ‘tomb aspects’ of Phase 3 are seen to represent the subjugation of the Oksung-ri political group by the Saro-guk polity, at the time when Saro-guk developed into the ancient state, Silla.