Review of Taejo Wanggeon’s family root and Goryo northern territory - Based on multi-family roots andKitan's tributary letters

Kim Gwan-eui's 『Pyeonnyeontongrok』, described that it was inevitabe that Taejo Wang-Geon was born in the background of achieved virtue and wealthy, with his ancestors Hogyeong and Kang Chung, who lived in the Paesu region(浿水), and ancestor Jakjegeon who decorated with strong Goguryeo folktale elements. Thus, there is an opinion that his family was successful Goguryeo refugees who were sent to the Ganghoe(江淮) region, on that point I also agree with that ,and the meaning of 'Janghoemujok(張淮茂族)' recorded in the tributary letter of Taejo and Seongjong sent by LaterTang and Song became the northern ancestry theory. In this paper, the author revealed that Wang Bong-gyu, the Silla Quanzhou judiciary(泉州節度使) who sent Im-Eon(林彦) as an envoy to LaterTang to pay tribute along with King Gyeong-ae(景哀王), was the Goryo Taejo through a comparison of 『Samguksagi』 and 『Goryeosa』texts, and that he was a Silla official who managed Quanzhou(泉州) in the Minyue(閩越)region at the time. The district name and official system were explained as examples. His dubious family origination was due to the fact that historians referred to insufficient Chinese records due to the Annals of the seven generations from Taejo, which were burnt out during the Khitan invasion. During the chaotic Five Dynasties era, the territory of Goryeo's region that Taejo defended during the territorial war with the Khitan was the area east of the Hondong River(混同江) where was the Goguryeo region. The Goryeo region, based on the Khitan's tributary letter from Seongjong to Yejong, even changed with the times, but was generally from the eastern area of Yalu River(鴨綠), through Sanggyeong Yongcheonbu(上京龍泉府), to Seonchunryeong(先春嶺). For this reason, it is thought that the phrase ‘一隅連陸, 輻員之廣, 幾於萬里’ may be record in the preface to the geography of 『Goryeosa(高麗史)』.