, also romanized as Ō-an, was a Japanese era name (年号, nengō, lit. year name) of the Northern Court during the Era of Northern and Southern Courts after Jōji and before Eiwa. This period spanned the years from February 1368 through February 1375.[1] The emperors in Kyoto were and [2] The Southern Court rival in Yoshino during this time-frame was .
During the Meiji period, an Imperial decree dated March 3, 1911 established that the legitimate reigning monarchs of this period were the direct descendants of Emperor Go-Daigo through Emperor Go-Murakami, whose had been established in exile in Yoshino, near Nara.[3]
Until the end of the Edo period, the militarily superior pretender-Emperors supported by the Ashikaga shogunate had been mistakenly incorporated in Imperial chronologies despite the undisputed fact that the Imperial Regalia were not in their possession.[3]
This illegitimate had been established in Kyoto by Ashikaga Takauji.[3]
In this time frame, Shōhei (1346–1370), Kentoku (1370–1372) and Bunchū (1372–1375) were Southern Court equivalent nengō.