Kōgen

Kōgen was a Japanese era name after Kenchō and before Shōka. This period spanned the years from October 1256 to March 1257. The reigning emperor was Emperor Go-Fukakusa.

Change of era

1256 Kōgen gannen: 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 : Kujō Yoritsune, also known as Fujiwara Yoritsune, died at the age of 39 years.October 14, 1256 : Yoritsune's son and successor as Kamakura shōgun, Kujō Yoritsugu, also known as Fujiwara Yoritsugu, died at the age of 18 years.