He entered the Buddhist temple of Daming at the age of 14. He studied at Chang’an (Ch’ang-an) for six years, starting at the age of 20. He then returned to the Daming Temple where he eventually became the abbot of the temple.
He also trained in medicine and opened a hospital, the Beitian Court, at the Daming Temple. In 732 c.e. the Japanese government sent an emissary to China, including two priests searching for a precept transmitter to come to Japan.
In 742 they met with Ganjin and his followers. none of Ganjin’s followers was willing to go, so he decided to go himself. The crossing from China to Japan across the East China Sea was dangerous, and it took six tries before Ganjin reached Japan in 753. During the fifth attempt, he lost his eyesight.
Ganjin was welcomed at the Japanese capital in 754. That summer, in front of the Great Buddha Hall at Todai-ji, a ceremony was held in which the retired emperor Shomu, the empress dowager Komyo, the reigning empress Koken, and 440 clergy received the precepts.
An order was issued to build a precept hall and living quarters for Ganjin. Ganjin’s arrival in Japan brought the transmission of the precept, in Japan, back toward a more orthodox way of doing it.
In 756 Ganjin was appointed to the bureau of clergy, which controlled the issuing of certificates for ordination. The Japanese viewed protecting the nation as part of the clergy’s mission. The Japanese government expected the priests to work in support of the nation’s prosperity.
The fact that Ganjin, who was Chinese, was appointed to the bureau speaks volumes about his skill and the level of his understanding of the Buddhist religion. Ganjin resigned from the bureau in 758 and returned to training priests. Ganjin continued to teach up until his death on June 22, 763. He is considered one of the founding fathers of Sino-Japanese medicine.