It was during this period in the investigation of Japanese history, scholars researching the external articles of "Nihonshoki," in a break through, identified through calculations was the correct dating of the events; the method used in calculation, was the movement backward in years by two cycles (one cycle = 60 years), 120 years, to the estimated sexagenarian cycle in the book.
この頃の『日本書紀』の対外的な記事には、推定干支を二運120年繰り下げる計算をすれば正しいと思われる記事がある。