Background
Tenno Kogen was the eldest son of Emperor Korei and Empress Kuwashi- hime-no-Mikoto, and originally ,named Oya- matonekohikokunikuru-no-Mikoto, who was born during the 18th year of his father's reign.
Tenno Kogen was the eldest son of Emperor Korei and Empress Kuwashi- hime-no-Mikoto, and originally ,named Oya- matonekohikokunikuru-no-Mikoto, who was born during the 18th year of his father's reign.
Tenno Kogen was invested Crown Prince (214 B.C.), after which he moved his capital to Karu, near Unebi (Nara Prefecture) and named it Sakaihara-no-Miya. He reigned for 57 years.
Modern scholars have come to question the existence of at least the first nine emperors; Kōgen's descendant, Emperor Sujin is the first that many agree might have actually existed.The name Kogen-tenno was assigned to him posthumously by later generations.
Kogen is regarded by historians as a "legendary emperor". There is insufficient material available for further verification and study.The reign of Emperor Kinmei (c. 509 – 571 AD), the 29th emperor, is the first for which contemporary historiography is able to assign verifiable dates;However, the conventionally accepted names and dates of the early emperors were not to be confirmed as "traditional" until the reign of Emperor Kanmu (737–806), the 50th sovereign of the Yamato dynasty.
In the Kojiki and Nihonshoki only his name and genealogy were recorded. The Japanese have traditionally accepted this sovereign's historical existence, and an Imperial misasagi or tomb for Kōgen is currently maintained; however, no extant contemporary records have been discovered that confirm a view that this historical figure actually reigned. He is considered to have been the seventh of eight emperors without specific legends associated with them, also known as the "eight undocumented monarchs".