This was the earthen fortress built along the riverside of Hangang in the early years of Baekje. It is commonly referred to as ‘Pungnap Toseong,’ (earthen fortress), and the current title was named because the structure belonged to the jurisdiction of Pungnap-ri, Gwangju-gun, Gyeonggi-do, Korea when designated as an historical site in 1963.
Originally, the fortress was built in the shape of an ellipsis, extending 2km toward the south and north, 1km toward the east and west, with a circumference of 3.5km. However, the west wall toward Hangang was destroyed during flooding in 1925, with only 2.7km of the wall currently remaining. The wall was built by hardening fine sand to a height of 9 - 15m, and a breadth of 40m. There are traces of the four gates of the east side.
As major relics, including a bronze cauldron with a handle and a belt accessory, were unearthed during the great flood of 1925, this fortress has attracted a great deal of attention, as it was assumed to be the Wirye on the south side of Hangang, even under Japanese rule. After liberation, the first excavation was undertaken by Seoul National University in 1966. They unearthed two layers of Baekje-era civilizations, and relics estimated to have been produced between 0 and 5 AD, including hard, pattern-less earthenware
In 1997, a number of earthenware relics from the Baekje period were discovered on the reconstruction site by a research team from Sunmoon University during a survey of the wall of the Pungnap Earthen Fortress. The National Research Institute of Cultural Heritage immediately dispatched an excavation and investigation team. As a result, they uncovered a triple moat settlement, a 19 flat and hexagonally 66m2 housing site, one earthenware kiln, a number of pitted settlements, numerous earthenware items, roof tiles, ironware, a 44 ‘呂’ shaped building site, and earthenware known as ‘Dafu.’ The site became an instant center of attention.
For its time of construction, the site’s condition, which includes a large river, along with the tumuli and a mountain fortress in the surrounding area, is comparable with fortresses of other kingdoms built around the same period, such as the Nakrang Earthen Fortress and Goguryeo’s Guknae Fortress. Additionally, considering the size of the population, the social structure, and the power structure, the construction of the huge earthen fortress around 3 AD suggested that the Pungnap Earthen Fortress was the royal fortress of the early years of the Baekje era.