In 804, the Buddhist monks Kūkai and Saichō arrived in China to study religion as part of a government-sponsored mission during the Heian period. The "Shōryōshū," written in 814, mentions that Kūkai drank tea during his time in China. He returned to Japan in 806. Kūkai is also the first to use the term , which later came to refer specifically to the Japanese tea ceremony. Upon their return to Japan, Kūkai and Saichō founded the Shingon and Tendai schools of Buddhism, respectively. One or both of them are thought to have brought back the first tea seeds to Japan during this trip. Saichō, who returned in 805, is often credited for being the first to plant tea seeds in Japan, although the documentary evidence is uncertain.