Mountain Buddhism (山岳仏教)
Mountain Buddhism, a form of Buddhism for the practitioner of austerities who seeks an ascetic practice place in mountains, was begun by Saicho (767-822), the founder of the Tendai sect, Kukai (774-835), the founder of the Shingon sect, and others against the secularization of Nara Buddhism (Nanto rokushu), which had strengthened its ties with the government. It led to the Shugendo (Japanese mountain asceticism/shamanism incorporating Shinto and Buddhist concepts) and developed rapidly during the Heian period, combined with the traditional Japanese mountain worship.
It is said that Buddhism was introduced to Japan in 538, which was the era of Emperor Kinmei. During the Heian period (794 to 1192), the Tendai and Shingon sects were established by Saicho and Kukai, respectively, who practiced asceticism and had learned orthodox Mountain Buddhism in Tang, and some temples (including those of Mt. Hiei and Mt. Koya) were founded. Enryaku-ji Temple of Mt. Hiei was founded by Saicho in 788, and Kongobu-ji Temple of Mt. Koya was founded by Kukai in 816. Implying their criticism of urban Buddhism, which tended to be political, they strengthened the characteristic of Mikkyo (Esoteric Buddhism) despite the call to keep the nation tranquil, and distanced themselves from government. It can be assumed that because there are many mountains in Japan and a traditional mountain worship had existed, this kind of idea could easily have been accepted. Additionally, from the standpoint of practical benefit, the development of Mountain Buddhism was promoted because the aristocracy expected the genriki (the effect) of the ascetic monk to bring spiritual (material) benefit in this world through the observance of Buddhist teachings, and it was also protected by the Imperial Court (including the Imperial Family), which led to a rapid generalization. In 806, Mountain Buddhism officially became one of the kokka bukkyo (Buddhism for ruling the country) as well as the urban form of Buddhism. A method in Esoteric Buddhism, which included strong characteristics of the benefit gained in this world and Onmyodo (the way of Yin and Yang, and occult divination system based on the Taoist theory of the five elements) also developed, as did the Jodo sect founded by Honen. It also led to the Shugendo, which emphasized the mountain ascetic practices, and an idea of syncretism of Shinto and Buddhism was created. However, its religious group became enormous and purified during the Heian period.
The mountains worshipped in Mountain Buddhism
Dewa Sanzan (Three Mountains of Dewa)