Japanese Zen is derived from the Japanese pronunciation of the Middle Chinese word 禪 (Chan) which traces its roots to the Indian practice of dhyāna ("meditation"). Buddhism was introduced to China in the first century CE. According to tradition, Chan was introduced around 500 CE by Bodhidharma, an Indian monk teaching dhyāna. He was the 28th Indian patriarch of Zen and the first Chinese patriarch. Buddhism was introduced in Japan in the 8th century CE during the Nara period (710-794) and the Heian period (794–1185). Zen was not introduced as a separate school in Japan until the 12th century during the Kamakura
Zen at War types of social discrimination found in Sõtõ rituals and temple practices" find their origin in "the medieval institutional regulations imposed by the Tokugawa regime, not in the religious attitudes, religious practices, or religious mission of Sõtõ Zen itself". The Soto-school has installed a Human Rights Division, to terminate the regulations which contribute to discriminatory practices. "Zen at war" has contributed to discussions on the meaning of "enlightenment", and the role of Zen-teachers in the emerging western Zen-Buddhism. Bodhin Kholhede, dharma heir of Philip Kapleau, says: Stuart Lachs has written several essays on this issue, connected to teacher-scandals in western sanghas.