The Taira (平) was one of the four most important clans that dominated Japanese politics during the Heian period of Japanese history – the others being the Minamoto, the Fujiwara, and the Tachibana. The clan is divided into four major groups, named after the emperors they descended from: Kanmu Heishi, Ninmyō Heishi, Montoku Heishi, and Kōkō Heishi, the most influential of which was the Kanmu Heishi line.

Emperor Kanmu , or Kammu, was the 50th emperor of Japan, according to the traditional order of succession. Kammu reigned from 781 to 806, and it was during his reign that the scope of the emperor's powers reached its peak.