Zen was first introduced into Japan as early as 653-656 in the Asuka period (538–794), at the time when the set of Zen monastic regulations was still nonexistent and Chan masters were willing to instruct anyone regardless of buddhist ordination. Dōshō (道昭, 629–700 C. E. ) went over to China in 653, where he learned Chan from the famed Chinese pilgrim Xuanzang (玄奘, 602 – 664) , and he studied more fully with a disciple of the second Chinese patriarch, Huike (慧可, 487–593) . After returning home, Dōshō established the Hossō school, basing it on Yogācāra philosophy and built a Meditation Hall for the purpose of practising Zen in the Gangō-ji in Nara. In the Nara period (710 to 794), the Chan master, Dao-xuan (道璿, 702-760), arrived in Japan, he taught meditation techniques to the monk Gyōhyō (行表, 720–797), who in turn was to instruct Saichō (最澄, 767-822), founder of the Japanese Tendai sect of Buddhism. Saicho visited Tang China in 804 as part of an official embassy sent by Emperor Kammu (桓武天皇, 781-806). There he studied four branches of Buddhism including Chan and Tiantai, which he was, by that time, already familiar with.