Kōgen

Kōgen (康元) was a Japanese era name (年号) after Kenchō and before Shōka. This period spanned the years from October 1256 to March 1257. The reigning emperor was Go-Fukakusa-tennō (後深草天皇).

Change of era

 * 1256 Kōgen gannen (康元元年): The new era name was created to mark an event or a number of events. The previous era ended and a new one commenced in Kenchō 8.

Events of the Kōgen era

 * September 1, 1256 (Kōgen 1, 11th day of the 8th month): Kujō Yoritsune, also known as Fujiwara Yoritsune, died at the age of 39 years.
 * October 14, 1256 (Kōgen 1, 24th day of the 9th month): Yoritsune's son and successor as Kamakura shōgun, Kujō Yoritsugu, also known as Fujiwara Yoritsugu, died at the age of 18 years.