Osan Discovers Three Kingdoms-Era Fortress Wall of Doksan Fortress, Previously Known Only Through Historical Records

[Suwon Ilbo=Seo Dong-young Reporter] Osan City announced on the 29th that an academic excavation survey of Historic Site No. 140, Osan Doksan Fortress and Semadae Site (hereinafter Doksan Fortress), being conducted by the Central Archaeology Research Institute and Hanshin University Museum, has confirmed fortress walls from the Three Kingdoms period.

The survey began after bulging and deterioration phenomena were detected in portions of the fortress walls around the northeastern sector and north gate area of Doksan Fortress. Prior to repairs and maintenance of the fortress walls, the survey aimed to confirm the structure and construction methods of the original fortress walls buried beneath the restored stone walls to secure foundational research data.

The excavation results revealed fortress walls from both the Three Kingdoms and Joseon Dynasty periods buried beneath the restored walls for the first time. The Three Kingdoms-era fortress walls were located beneath the Joseon Dynasty fortress walls.

A city official stated, "It is difficult at this point to announce which of the three kingdoms—Goguryeo, Silla, or Baekje—the fortress walls belonged to."

Until now, the overall appearance of the fortress during the Joseon Dynasty could be inferred from surviving remnants. However, for the Three Kingdoms period, only historical documents had confirmed the existence of the fortress.

The Three Kingdoms-era fortress walls are estimated to have been constructed using both the gangchuk (夾築) method of building inner and outer walls together and the pyeonchuk (片築) method of building only the outer wall, with techniques varying according to the terrain. The outer walls were generally built using rectangular or square stone blocks, though some sections used elongated rectangular stones. They are understood to have been rebuilt multiple times.

Below the outer walls, a foundation reinforcement course was constructed and clay was applied to strengthen the base of the fortress walls. The inner walls were confirmed only in some sections and reach approximately 4 meters in height. Unlike the outer walls, the inner walls were constructed by stacking unworked stone blocks in even layers.

The Joseon Dynasty fortress walls were built atop the upper surface of the Three Kingdoms through Unified Silla-era fortress walls. Notably, beneath the north gate estimated to have been constructed in the late Joseon period, a gate site and defensive structures corresponding to the early Joseon period were confirmed. Additionally, crenellations (女墻) were found on the upper portion of the inner slope facing the fortress interior, and stepped stone terrace facilities constructed to allow easier ascent and descent inside the fortress were built in both longitudinal and transverse directions.

Artifacts unearthed include pottery shards from the Three Kingdoms through Unified Silla period (stamped pattern pottery shards, pedestal cup fragments, etc.), decorative roof tiles with lotus motifs, geometric pattern tiles, celadon fragments and spherical bottles from the Goryeo period, and pottery shards, white porcelain fragments, roof tiles with various patterns, and tile brick fragments from the Joseon period. Based on the fortress wall construction techniques and excavated artifacts, the site is judged to have been initially constructed during the Three Kingdoms period (6th-7th century) and continuously operated through the Joseon Dynasty period (15th-18th century).

A city official stated, "Through the excavation survey, foundational research data has been secured that allows us to understand the initial construction period and repair aspects of Doksan Fortress," and added, "It is expected to provide valuable materials for research on the defensive systems and mountain fortresses in the Seoul and Gyeonggi regions."

Meanwhile, the city and the survey institutions will hold a public information session on December 4th at 10:30 a.m. for the general public and researchers. For details and participation in the site unveiling, contact Hanshin University Museum (031-379-0195).