Jōgan (貞観) was a Japanese era name (年号,, nengō,, lit. "year name") after Ten'an and before Gangyō. This period started in April 859 and ended in April 877.[1] During this time, the emperors were Seiwa-tennō (清和天皇) and Yōzei-tennō (陽成天皇).[2]
Events of the Jōgan era
859 (Jōgan 1, 1st month): New Year's festivities were suspended during national mourning for the death of Emperor Montoku.[3]
864 (Jōgan 6, 5th month): Mount Fuji erupted during 10 days. Cinders and ash fell to earth as far away as Kai Province.[4]
869 (Jōgan 10): Prince Sadaakira was born. He will later become Emperor Yōzei.[5]
870 (Jōgan 11): Sadaakira was named Seiwa's heir.[5]
876 (Jōgan 17, 11th month): In the 18th year of Seiwa's reign, the emperor abdicated. His five-year-old son received the succession (senso).[6] Soon after,[7] Emperor Yōzei accepted the monarch's role and duties and powers (sokui).[5] This was confirmed in ceremonies.[8]
A collection of laws issued after 811 was published during this era. It was called the Jōgan kyaku-siki.[9]
♯The Northern pretenders did not recognize the Genkō era. Gentoku was used in the Northern Court until 1332. ₪The Shōkyō era was recognized only by the Northern pretenders, not by the Southern Court. ‡ Upon reunification of the Northern and Southern Courts in 1392, Genchū was discontinued. Meitoku was used until 1394.