Reconsidering the location of Bohai(渤海) Sea from Han(漢) to Tang(唐) Dynasties

Bohai(渤海) Sea, which was crossed by Han(漢) Dynasty in 109 BC when Han(漢) attacked Gojoseon(古朝鮮), and Bo'xie(勃澥) Sea which was crossed by Sui(隋) Dynasty in 612 AD when Sui(隋) attacked Goguryeo(高句麗) were the same sea, but they were not the current Bohai(渤海) Sea that is the northern sea of the current Yellow Sea(黃海). At that time, Bohai(渤海) Sea was like a huge inland lake in the lower part of the Yellow River. This fact can be confirmed by many records of Bohai flooding, Bohai's bank bursting, and Bohai's distance from Luoyang(雒陽). The fact that the ancient cities related to Bohai were located in the north and south around the Yellow River also corroborates it. Shiji(史記) records there were two seas which were close to Gojoseon(古朝鮮) during the Earlier Han(前漢) period, the Bohai Sea(渤海) and the North Sea(北 海), and they were different seas which existed at the same time. Specifically, it is proved by this study that the ancient Bohai Sea(渤海) was in the southern Hebei Province(河北省) of China, and the current Bohai Sea was called as the North Sea(北海). Therefore, the Bohai Sea(渤海, 勃澥) that Han(漢) Dynasty and Sui(隋) Dynasty had crossed to attack Gojoseon and Goguryeo can not be the current Bohai Sea(past North Sea), but the ancient Bohai Sea, which was inland in the Central Plain(中原) of China. These fact proves that the current global scholars’ assignment of the capitals of Gojoseon and Goguryeo to Pyongyang(平壤), North Korea, is most likely in error. This is because if the Bohai Sea(渤海) was inland in the Central Plain(中原) of China, it means that the Han(漢) and Sui(隋) dynasties crossed the sea that was not the sea that they had to cross to attack Pyongyang(平壤), North Korea. In other words, it can be inferred that the capitals of Gojoseon and Goguryeo were in the northern part of present-day Hebei Province (near Beijing) of China, not in the Korean Peninsula.