Seon was taken to Vietnam as early as the second century CE through the North from central Asia and via Southern routes from India. It has had a symbiotic relationship with Taoism, Chinese spirituality, and the indigenous Vietnamese religion. Buddhism is not practiced the same as in other Asian countries and does not contain the institutional structures, hierarchy, or sanghas that exist in other traditional Buddhist settings. Many Vietnamese define their spiritual needs using a Buddhist worldview.
By the end of the second century, Vietnam developed a major Buddhist centre (probably Mahayana) in the region, commonly known as the Luy Lâu centre, now in the Bắc Ninh province, north of the present day Hanoi city. Luy Lâu was the capital of Giao Chỉ, (the former name of Vietnam), and was a popular place visited by many Indian Buddhist missionary monks to China. The monks followed the sea route from the Indian sub-continent to China used by Indian traders. A number of Mahayana sutras and the Agamas were translated into Chinese script at that centre, including the Sutra of Forty-Two Chapters and the Anapanasati.
Over the next 18 centuries Vietnam and China shared many common features of cultural, philosophical and religious heritage. This was due to geographical proximity to one another and Vietnam being annexed twice by the Chinese. Vietnamese Buddhism has been greatly influenced by the development of Mahayana Buddhism in China, with the dominant traditions of Pure Land and Ch’an/Zen. Theravada Buddhism would become incorporated through the annexation of the Khmer land and khmer people.
During the Đinh Dynasty (968-980) Buddhism was recognized by the state as an official religion suggesting that the current kings at the time held Buddhism in high regard. The Early Lê Dynasty (980-1009) would follow a similar path. Reasons for growth of Buddhism during this time is contributed to an influx of educated monks, a newly independent state needing an ideological basis on which to build a country and the development of Confucianism. Buddhism became more prominent during the Lý Dynasty (1009-1225) beginning with the founder Lý Thái Tổ who was raised in a pagoda (Buddhist temple). All of the kings during the Ly Dynasty supported Buddhism as a state religion and this continued into the Trần Dynasty (1225-1400) where Buddhism later developed in combination with Confucianism. Buddhism fell out of favor during the Later Lê Dynasty and would grow under the Nguyễn Dynasty.
A Buddhist revival started in 1920, but under Communist rule many religious practices in Vietnam Buddhism were suppressed. However a government sanctioned and approved United Buddhist Church was created in the North. In the South, The Unified Buddhist Church was created and opposed the communist government.
Thien Buddhism (Thien Tông) is the Vietnamese name for the school of Zen Buddhism. The traditional account is that in 580, when an Indian monk named Vinitaruci (Vietnamese: Tì-ni-đa-lưu-chi) traveled to Vietnam after completing his studies with Jianzhi Sengcan, the third patriarch of Chinese Zen. This would be the first appearance of Vietnamese Zen, or Thien (thiền) Buddhism. The sect that Vinitaruci and his lone Vietnamese disciple founded would become known as the oldest branch of Thien. After a period of obscurity, the Vinitaruci School became one of the most influential Buddhist groups in Vietnam by the 10th century, particularly under the patriarch Vạn-Hạnh (died 1018). Other early Vietnamese Zen schools included the Vo Ngon Thong (Vô Ngôn Thông), which was associated with the teaching of Mazu, and the Thao Duong (Thảo Đường), which incorporated nianfo chanting techniques; both were founded by Chinese monks. A new school was founded by King Trần Nhân Tông (1258–1308); called Trúc Lâm (Bamboo Grove) school, which evinced a deep influence from Confucian and Taoist philosophy. Nevertheless, Trúc Lâm’s prestige waned over the following centuries as Confucianism became dominant in the royal court. In the 17th century, a group of Chinese monks led by Nguyên Thiều introduced the Ling school ( Lâm Tế). A more domesticated offshoot of Lâm Tế, the Liễu Quán school, was founded in the 18th century and has since been the predominant branch of Vietnamese Zen.
Seon was taken to Japan by Korean missioners in the 12th century. Currently, there are three main Zen schools in the Country: Sōtō, Rinzai, and Obaku. In the 1960s, Japanese masters moved to North America and contributed to the spread of Seon/Zen; many of the Seon terms which are familiar, even to people not practising it, are in their Japanese version. Soon, American-born masters started to spread Zen in USA and Canada.
Nanpo Shōmyō (1235–1308) studied Linji teachings in China before founding the Japanese Otokan lineage, the most influential branch of Rinzai. In 1215, Dōgen, a younger contemporary of Eisai’s, journeyed to China himself, where he became a disciple of the Caodong master Tiantong Rujing. After his return, Dōgen established the Sōtō school, the Japanese branch of Caodong. The Obaku lineage was introduced in the 17th century by Ingen, a Chinese monk. Ingen had been a member of the Linji school, the Chinese equivalent of Rinzai, which had developed separately from the Japanese branch for hundreds of years. Thus, when Ingen journeyed to Japan following the fall of the Ming Dynasty to the Manchus, his teachings were seen as a separate school. The Obaku school was named for Mount Obaku (Chinese: Huangboshan), which had been Ingen’s home in China.