According to "Nihonshoki" (Chronicles of Japan), when Kanyamato Iwarehiko (Kamuyamatoiwarebiko) was 45 (age by the traditional Japanese system), or some 1,792,470 years after Amatsuoya Ninigi descended to the earth, he said that there were numerous disputes in the far land and heard from Shiotsuchinooji about a beautiful province in the east, so he set out for the eastern expedition to build the capital.
『日本書紀』では神日本磐余彦（カムヤマトイワレビコ）は45歳（数え）の時、天祖ニニギが天降ってから179万2470余年になるが、遠くの地では争い事が多く、塩土老翁（シオツツノオジ）によれば東に美しい国があるそうだから、そこへ行って都を作ろうと思うと言って、東征に出た。