Kōgen (康元) was a Japanese era name (年号, nengō,, lit. "year name") after Kenchō and before Shōka. This period started in October 1256 and ended in March 1257. The reigning emperor was Go-Fukakusa-tennō (後深草天皇).
Events of the Kōgen era[change]
- 1 September 1256 (Kōgen 1, 11th day of the 8th month): Kujō Yoritsune, also known as Fujiwara Yoritsune, died at the age of 39 years.
- 14 October 1256 (Kōgen 1, 24th day of the 9th month): Yoritsune's son and successor as Kamakura shogun, Kujō Yoritsugu, also known as Fujiwara Yoritsugu, died at the age of 18 years.