GenninGennin was a Japanese era name after Jōō and before Karoku. This period spanned the years from November 1224 to April 1225. The reigning emperor was Emperor Go-Horikawa.Change of era1224 Gennin gannen: The era name was changed to mark an event or a number of events. The previous era ended and a new one commenced in Jōō 3.Events of the ''Gennin'' Era1224 : Kyogyoshinsho was believed to have been composed in 1224; and this is also considered the year in which Jōdo Shinshū was founded.