Jōan (承安) was a Japanese era name (年号,,nengō,, lit. "year name") after Kaō and before Angen. This period spanned the years from April 1171 through July 1175. The reigning emperor was Takakura-tennō (高倉天皇).
1171Jōan gannen (承安元年): The new era name was created to mark an event or series of events. The previous era ended and a new one commenced in Kaō 3, on the 21st day of the 4th month of 1171.
Events of the Jōan era
1172 (Jōan 1, 3rd day of the 1st month): The emperor had attained the age of 11 years; accordingly, the hair on his head was shaved as a sign of his coming of age.
1171 (Jōan 1, 13th day of the 1st month): The young emperor made a visit to the home of former-Emperor Go-Shirakawa, where he first met Tiara-no Tokoku, the adopted daughter of Go-Shirakawa and the actual daughter of Taira no Kiomori. He accepted the 15-year-old girl as one of his consorts, and she moved into his palace.
1171 (Jōan 2, 10th day of the 2nd month): Taira Kiyomori's daughter, Tokuko, becomes Emperor Takakura's his secondary empress (chūgo).