Most of these ascetics, in addition to their devotion to shugendō, studied the teachings of the Tendai sect of Buddhism, or the Shingon sect, established by Kōbō Daishi in the 8th century. Shingon Buddhism was one of the primary sects of mikkyō (密教) or Esoteric Buddhism, according to which enlightenment is found through isolation, and the study and contemplation of oneself, as well as nature, and esoteric images called mandala. Both the Shingon sect and the Tendai viewed mountains as the ideal place for this sort of isolation and contemplation of nature.