According to Inoue, the name of Mimana Nihon-fu can be found in "History of Baekje," which is quoted in "Nihonshoki," and although the name of 'Wa' (倭) originally meant the various districts in the southern area of the Korean Peninsula as mentioned in the account of Korea in "Records of Wei" ("Sangokushi" [Three Kingdoms Saga]), Baekje in the end of sixth century used the word as if it was related to the government of wajin (倭人, people of Wakoku) in the Japanese archipelago, trying to win their favor and support in order to compete with Goguryeo and Silla, which unintendedly gives the impression that the power of Yamato sovereignty extended to the southern area of the Korean Peninsula early on.
井上によると、任那日本府とは『日本書紀』が引用する『百済本紀』において見られる呼称であり、6世紀末の百済が高句麗・新羅に対抗するために倭国（ヤマト王権）を懐柔しようとして、『魏志』（『三国志(歴史書)』）韓伝において朝鮮半島南部の諸国を表していた「倭」と、日本列島の倭人の政権とを結びつけて、ヤマト王権の勢力が早くから朝鮮半島南部に及んでいたかのような印象を与えるに過ぎない。