Ten'an 1 (天安元年)
Timeline of 857
- 1/17 The Goki-reki calendar is adopted in place of the Taien-reki calendar.
- 2/19 Udaijin Fujiwara no Yoshifusa becomes Dajô Daijin and is replaced as Udaijin by Fujiwara no Yoshimi. Minamoto no Makoto is appointed Sadaijin.
- 4/23 The Ôsaka-no-seki barrier is re-established, and new barriers at constructed at Ôishi-no-seki (in Ômi province) and Ryûge-no-seki (in Yamashiro province).
- 6/25 The Dazaifu reports that some lower-ranking officers attacked the governor (kami) of Tsushima province, setting fire to his home and killing the governor, ten of his men, and six sakimori (coast guards).
Other Events of 857
- Fujiwara no Yoshifusa becomes sesshô. This is the first time someone outside the Imperial family is appointed to the position, and it marks the beginning of a lengthy period of Fujiwara clan domination of the position.