The Baekje Dynasty restoration movement that came into existence right after the collapse of the Baekje Dynasty in July 660 rapidly declined with the Baekganggu Battle in August 663 and the Juryuseong Castle battle in September 663. The Combined Restoration Army of Baekje Dynasty and Japanese Armed Forces blocked and engaged in a close-range battle with the Combined Silla-Tang Armed Forces at the entrance of the Baekgang River, but were heavily defeated. The Juryuseong Castle, which was the central base of the Restoration Army of Baekje Dynasty, was taken over by the Combined Silla-Tang Armed Forces. The defeat in these two battles resulted in the Baekje Dynasty restoration movement practically coming to an end. There was no consensus reached on the location of the Baekgang River and the Juryuseong Castle, which are important elements in Baekje Dynasty restoration movement research.
There are various theories on the location of the Baekgang River in relation to the location of the Juryuseong Castle: the Geumgang River estuary theory; the Dongjingang River theory; the theory that suggests that the location was near Julpo of Buan; and the theory that the location was near Asanman Bay. Most agree that the entrance of the Baekgang River, where the Combined Silla-Tang Armed Forces landed in July 660, was the estuary of the Geumgang River, but there is confusion because some view the entrance of the Baekgang River where there was a big battle between the Combined Restoration Army of Baekje Dynasty and the Combined Silla-Tang Armed Forces that marched forward towards the Juryuseong Castle in August 663 as a different location. This led to a problem: Many suggested that the location of the Baekgang River, which was at the entrance of the Geumgang River in July 660, changed in August 663, and no consensus was reached on the changed location. However, there is almost no possibility of the location of the Baekgang River changing from here and there in just a few years. The entrance of the Baekgang River, where the Combined Silla-Tang Armed Forces landed to attack the Sabidoseong, Capital City of Baekje in July 660, is the same place as the Gibeol Inlet, and therefore the Baekgang River of August 663 refers to the Geumgang River. There is no doubt that the Gibeol Inlet, where the Combined Silla-Tang Armed Forces battled in July 676, was the estuary of the Geumgang River, and thus the Baekgang River is clearly the Geumgang River.
The Juryuseong Castle was the southern base of the Restoration Army of Baekje Dynasty. This castle and the Imjonseong Castle in the north were the two key strongholds of the Baekje Dynasty restoration movement. The castle is especially where the leaders of the Restoration Army of Baekje Dynasty were stationed. Although it is widely known as a key location of the movement, its exact location is not known. A clue to the location is given in the Nihonsyoki (Chronicles of Japan) in which it states that the castle was located on a rugged mountain where the lands were barren, far away from farmlands. There were various theories in relation to the location of the Baekgang River because of the attempts to identify a location that has the geographical conditions mentioned above and that is not too far away from the Baekgang River. Theories that locate the castle in the northern part of the Geumgang River are as follows: the Hansan theory; the Yeongi theory; the Jubongsangseong Castle theory; and the Biin theory. Those theories that locate the castle in the southern part of the Geumgang River are as follows: the Wegeumamsanseong Castle in Buan theory; the Suryumyeon in Gimje theory; and the Chilbomyeon in Jeongeup theory. With the exception of the Wegeumamsanseong Castle in Buan theory, these theories have many issues. In particular, they are completely out of line with the location of the Juryuseong Castle described in the Nihonsyoki. It is clear that the entrance of the Baekgang River is today's estuary of the Geumgang River. If we find a place that is located on a rugged mountain where the lands are barren and far away from farmlands, there is no place like Mt. Byeonsan of Buan. In other words, the Juryuseong Castle is none other than the Wegeumamsanseong Castle, which is a large castle with a valley inside, covering an area of 890,488㎡, with a width of 3,724 meters, located in Mt. Byeonsan of Buan.