Emperor Keikō (景行天皇) was the twelfth imperial ruler of Japan to appear on the traditional list of emperors. No firm date can be assigned to this emperor and he is regarded by historians as a "legendary emperor". This does not necessarily imply that no such person ever existed, just that there is insufficient material to assign him to a historical period.
His legend was recorded in Kojiki and Nihonshoki, but the accounts of him are different in these two sources. In Kojiki he sent his son Yamatotakeru to Kyushu to conquer local tribes. In Nihonshoki Keiko himself went there and won battles against local tribes. According to both sources, he sent Yamatotakeru to Izumo province and eastern provinces to conquer the area and spread his territory.
