One of the key remains of the Seoju era that is assumed to be the remains of a capital city, tracing back to the initial stage of the Yeon , and is situated at the town of Yuriha Bangsan-gu, Beijing. The size of the remain stands at approximately 5 million m2, and its existence was first confirmed during the 1940s.

After the 1970s, China's Social Science Archeology Center and Beijing Archeology Research Center conducted research and excavation.

Remains of a castle during the Seoju era is confirmed at approximately 800m for the northern wall, and 300-something m for the eastern and western walls. As for the width of the castle wall, the lower width is approximately 10m. From the outer part of the castle wall, a moat was found whereas inside of the castle, building sites were found. Other excavations include stone works, earthenware, bronze works, okgi, golgi, shell works and all types of tools of production, for daily livelihood, weapons, ornaments, bokgol and so forth.

A number of tombs of the Seoju era were found at the vicinity of the castle site. In the two tombs, found at the southwest of the castle site, yurijeom, remain of the sajaden's lower class culture that corresponds to the latter stage of the sangdae was discovered. In a tomb of the southeast part of the castle site hwangtopa that measures up to 50,000m2, large tombs of the Seoju were discovered. Among the 200-something tombs that were excavated, there are large, medium and small sized oblong dugout tomb, baechong, chamagang and so forth. Given the reputation of the bujang's bronze era, it is possible to deduce that they are the tombs of the nobility of the Yeon.

Compared to the Yeonhado, Liwolihuh (���츮��) remains are said to be the remains of a capital city during the early stage of the Yeon, which is slightly earlier, when the remains and relics excavated at the castle site and tombs are analyzed.