Kōhei (康平?) was a Japanese era (年号,, nengō,?, lit. "year name") after Tengi and before Jiryaku. This period spanned the years from August 1058 through August 1065. The reigning emperor was Go-Reizei-tennō (後冷泉天皇?).
Read more about Kōhei: Change of Era, Events of The Kōhei Era