Caodong school
Beomnang (法朗; fl. 632–646), said to be a student of the Chinese master Daoxin (道信; 580–651), is generally credited with the initial transmission of Chan into Korea. It was popularized by Sinhaeng (神行; 704–779) in the latter part of the eighth century and by Doui (道義; died 825) at the beginning of the ninth century. From then on, many Koreans studied Chan in China, and upon their return established their own schools at various mountain monasteries with their leading disciples. Initially, the number of these schools was fixed at nine, and Korean Seon was then termed the "nine mountain schools" (九山 or "gusan"). Eight of these were of the Mazu Daoyi (馬祖道一; 709–788) lineage, as they were established through connection with either him or one of his eminent disciples. The one exception was the Sumi-san school founded by Ieom (利嚴; 869–936), which had developed from the Caodong school (曹洞).