Baekje’s Ambition Buried in the Soil of Chungju

Panchuk Construction Previously Used Only for Royal Fortresses Found at Jangmisan Fortress
Discovery Includes 80,000-Liter Wooden Reservoir and Central-style Artifacts
"A Rare Complex Integrating Residential, Burial, Production, and Defensive Spaces"

Chungju Jangmisanseong Earthen Wall / Cultural Heritage Administration.

In the cross-section of the fortress wall at Jangmisan Fortress in Chungju, North Chungcheong Province, layers of compacted earth have been revealed. These are traces of "panchuk" (rammed earth), a method in which earth is placed in a rectangular frame and compacted to a fixed thickness. This advanced construction technique required skilled labor and large-scale resources, and until now has mainly been identified at royal Baekje fortresses in Seoul, such as Pungnap Toseong and Mongchon Toseong. Why did Baekje invest such royal-level engineering in Chungju, far up the Namhan River from Hansung (Baekje's capital)?

Designated as a historic site in 1997, Jangmisan Fortress is a contour fortress with a circumference of about 2,940 meters. It encircles the summit of Jangmisan and a valley, providing a panoramic view of both the Namhan River and the Chungju Basin. On September 1, 2026, the National Heritage Research Institute’s National Jungwon Heritage Research Center, which has been excavating the site since 2022, unveiled the site to the public and announced their findings: Jangmisan Fortress served as a key military and transportation hub for Baekje.

The decisive clue lay within the inner side of the rampart. The visible fortress wall consists of stonework the Silla Kingdom constructed after the 6th century. However, when the research team cut into a section of the wall, a completely different structure emerged beneath the stones: a Baekje-era panchuk earthen rampart, formed by building up and compacting layers of earth. Analysis of pottery unearthed alongside it dates the structure to the early 5th century.

Lim Jongdeok, Director of the National Heritage Research Institute, explained, "This demonstrates that Jangmisan Fortress was not simply a defensive structure, but a site where Baekje’s central technical and organizational prowess was deployed and operated."

Chungju Jangmisanseong Wooden Reservoir / Cultural Heritage Administration.

Royal-level civil engineering techniques can also be seen in the fortress’s internal water management facilities. In a northern valley, the largest wooden reservoir from the Hanseong period of Baekje was discovered. It is square-shaped, with each side measuring about 6.7 meters, and approximately 1.8 meters deep. The reservoir was built by interlocking chestnut and oak logs, over seven meters long, in nine stacked layers. The maximum storage capacity is about 80,000 liters—enough to supply 300 people for nearly two and a half months.

Despite the long passage of time, the preservation of the timber is remarkably intact. This is due to its being buried in soil that protected it from direct sunlight, while waterlogged mud prevented oxygen from reaching it. Choi Gwanho, Senior Researcher at the National Jungwon Heritage Research Center, said, “It is hard to believe this timber is 1,600 years old. In fact, across the entire period from the Three Kingdoms to Unified Silla, Jangmisan Fortress is the only site where such a well-preserved wooden storage facility has ever been found.”

The reservoir was not simply a water storage site. Broken pottery and various intact tools were intentionally placed or broken at the bottom. Lee Boram, Curator at the National Jungwon Heritage Research Center, explained, “These items were likely placed as ritual offerings during either the construction or use of the reservoir.”

Artifacts excavated at Jangmisan Fortress in Chungju / National Heritage Administration.

The earth holds a vivid record of the dietary life of fortress residents 1,600 years ago. The research team sieved and analyzed soil samples from the reservoir, finding microscopic artifacts and organic remains—including rice, soybeans, red beans, and wheat, as well as peaches, plums, wild grapes, raspberries, and water chestnuts. A wide variety of grains and fruits were identified.

An Soyeon, Researcher at the National Gyeongju Heritage Research Institute, noted, “This is the first time such a diversity of seeds and fruit have been found together in an ancient fortress. Particularly noteworthy are traces of rice polishing and rare burdock seeds.”

Bones of cattle, horses, pigs, dogs, and pheasants were also found. Ox bones show traces of dismemberment, indicating consumption within the fortress. In contrast, almost complete dog remains suggest they may not have been simple refuse, and may have had a ritual function.

Everyday tools used by the residents were also recovered near the animal bones. Notably, an iron axe with its wooden handle intact, the first such complete find in Korea, was unearthed. Judging by its form, it was likely used as a work tool rather than as a weapon. A winnowing basket and a cattle yoke, also found at the site, are the earliest physical specimens of their kind ever discovered in Korea. According to Researcher Lee, “These finds indicate that cattle were an important means of transporting goods within the fortress.”

The majority of the artifacts are believed to have been made in the early 5th century. The strong influence of central Baekje technology and culture is evident, to the extent that it is plausible they were brought in directly from Hansung. This suggests Baekje was consolidating its control over Chungju and actively committing both human and material resources to the region at the time.

Complete iron axe with a handle and cast iron parts unearthed from the excavation of Jangmisan Fortress in Chungju / Cultural Heritage Administration.

The key reason why Baekje invested so much effort in Jangmisan Fortress lies in “iron.” Since the Three Kingdoms period, the Chungju area was one of the peninsula’s leading iron production centers. Researcher Lee explained, “This would be comparable today to a major hub for cutting-edge industries like semiconductors. The fact that Baekje went so far as to transfer royal fortress construction technology underscores the high value they placed on Jangmisan Fortress.”

Its location as a critical transportation nexus is also significant. Chungju is at the junction of river routes along the Han River and overland routes to the Yeongnam region. In particular, the Mokgye ferry beneath Jangmisan served as a logistics hub with rafts passing through until the modern era; it took three days to go downstream to Noryangjin and Mapo, and about a week to return upstream. Overland from Chungju, one could transfer to routes through Mungyeong Saejae, Ihwaryeong, and Gyeryeong Pass to reach Yeongnam.

Noh Jungguk, Professor Emeritus of History at Keimyung University, described the Jangmisan Fortress area as “a rare example where residential, burial, production, and defensive facilities were integrated as a single complex.” Chungju not only attracted Baekje, but also Goguryeo and Silla, as all three kingdoms sought to secure this strategic hub. In fact, stone monuments left by Goguryeo and Silla tomb groups have both been discovered in the area.

The full story of the struggle among the Three Kingdoms for Chungju still lies buried underground. This investigation covered only 2,200 square meters out of a total area of 440,000 square meters at Jangmisan Fortress—just 0.5%. The remaining 99.5% is still an unexplored archaeological domain.

This content was produced with the assistance of AI translation services.