Jimon and Sammon

Jimon (寺門) and Sammon (山門), also known as the Enchin and Ennin factions, respectively, were rival branches of the Tendai sect of Buddhism created in the 9th century and based on Mount Hiei just outside Kyoto.

Jimon's head temple was Mii-dera, at the foot of Mount Hiei, while the Sammon sect was based at Enryaku-ji, at the summit of the mountain. This rivalry does not appear to be based on differing opinions on dogma or doctrine, only a sort of jealousy, each seeking to be the chief or sole Tendai core temple. Following the deaths of Enchin in 891, this rivalry only deepened, and over the next several centuries, led to a number of armed conflicts. Most were the result of a monk from one faction becoming appointed Abbot (zasu) of the other faction's temple, or of one faction not being invited to events, conferences, or festivals held by the other.

As the disagreements escalated into armed conflicts, both sects formed the first standing armies of warrior monks, called sōhei. When the Genpei War broke out in 1180, the warrior monks of the two sects found themselves on opposing sides, the Enryaku-ji Sammon monks supporting the Taira clan while Mii-dera's Jimon monks supported the Minamoto clan.