Caodong school () is a Chinese Chan Buddhist branch and one of the Five Houses of Chan.
The school emphasised sitting meditation (Ch: zuochan, Jp: zazen), and the "five ranks" teaching. During the Song dynasty, Caodong masters like Hongzhi Zhengjue developed "silent illumination" (mozhao) meditation.
The key figure in the Caodong school was founder Dongshan Liangjie (807âÂÂ869, æ´Âå±±è¯价, Jpn. Tozan Ryokai) and his heir Caoshan Benji (840âÂÂ901, æ¹山æ¬å¯Â, Ts'ao-shan Pen-chi, Jpn. Sà Âzan Honjaku). Some attribute the name "Caodong" as a union of "Dongshan" and "Caoshan". The "Cao" may also be from Cáoxë (æ¹溪), the "mountain-name" of Huineng, the Sixth Ancestor of Chan, as Caoshan was of little importance unlike his contemporary and fellow Dharma-heir, Yunju Daoying.
The Caodong school was founded by Dongshan Liangjie and his Dharma-heir Caoshan Benji. Dongshan traced back his lineage to Shitou Xiqian (700âÂÂ790), a contemporary of Mazu Daoyi (709âÂÂ788). Sayings to the effect that Shitou and Mazu were the two great masters of their day date from decades after their respective deaths. ShÃÂtóu's retrospective prominence owes much to the importance of Dongshan Liangjie. ShÃÂtóu does not appear to have been influential or famous during his lifetime:
In the 11th century the Caodong-school nearly extinguished. Dayang Jingxuan (942-1027), the last descendant of the Caodong-lineage passed on his dharma-transmission via Fushan Fayuan, a teacher from the Linji school, to Fayuan's student Touzi Yiqing (1032-1083), who was born five years after Jingxuan's death.
During the Northern Song (960âÂÂ1127) the Caodong was not successful in the social elite. The Linji school and Yunmen school dominated Chán. It was Touzi Yiqing's student Furong Daokai (1043âÂÂ1118) who was a successful monastic, and revived the Caodong school.
His dharma "grandson" Hongzhi Zhengjue (1091âÂÂ1157) became very successful among elite literati in the Southern Song (1127âÂÂ1279), when the Imperial Court decreased their influence on society, and Chán schools became dependent on elite literati for support. Under Hongzhi and Zhengzie Qingliao, the Caodong school was revived and became one of the major traditions of Song dynasty Chan.
These Song era teachers taught a practiced termed "silent illumination" or "serene reflection" (Ch: é»Â砧禠) which relied on the doctrine of inherent enlightenment and buddha-nature. Since Buddha was seen as something already present in the mind, all that one needed to do was to let go of all striving and this was achieved by silently sitting in meditation.
The success of the revived Caodong school drew opposition from Linji school figures like Dahui Zonggao, who promoted the Hua Tou method of koan practice, and attacked silent illumination as quietistic.
In 1227 Dà Âgen Zenji, a former Tendai student, studied Caodong Buddhism under Tiantong Rujing, and returned to Japan to establish the Sà Âtà  sect. His lineage incorporates not only the dharma-transmission via Fushan Fayuan, but also Linji dharma-transmissions via Eisai and his student Myozen, a teacher of Dogen, and the Linji dharma-transmission of Dahui Zonggao via the Nà Ânin school.
Caodong school was introduced to Korea at the end of Silla, through Seon master Ieom (å©å´, 869âÂÂ936). He arrived China in 894 and studied under teaching of Yunju Daoying. He returned to Silla in 911 and then established Sumi-san (é Âå½Âå±±) school to expand Caodong's teaching. He had several hundred students, his sect is one of Nine mountain schools. Later, the Nine mountain schools had been unified to Jogye Order by Jinul and Taego Bou.
In the 13th century, Dà Âgen Zenji studied the Caodong tradition and brought the teachings and techniques over to Japan, where it became known as Sà Âtà  Zen. Today, there are over 14,000 Sà Âtà  temples in Japan and Dà Âgen is regarded alongside Keizan as the Japanese traditionâÂÂs ancestors.
Caodong school is called "Tào ÃÂá»Âng tông" in Vietnamese. It was brought to the north Vietnam in the late of 17th century by Thiá»Ân master Thông Giác Thủy Nguyá»Ât (éÂÂ覺水æÂÂ, 1637-1704), a disciple of Yiju Zhijiao (ä¸Âå¥æºæÂÂ). Chan master Zhijiao is the 4th generation after Zhanran Yuancheng (æ¹Âç¶åÂÂæ¾Â, 1561-1626) - one of Caodong school's famous revivers in late Ming period.
via Shitou the Caodong traces back its origins to Huineng.