Buddhism in Vietnam (Đạo Phật 道佛 or Phật Giáo 佛教 in Vietnamese), as practiced by the Vietnamese, is mainly of the Mahayana tradition and is the main religion, a combination of Pure Land and Zen (Thiền). Buddhism may have first come to Vietnam as early as the 3rd or 2nd century BCE from the Indian subcontinent or from China in the 1st or 2nd century CE. Vietnamese Buddhism has had a syncretic relationship with certain elements of Taoism, Chinese spirituality, and Vietnamese folk religion. Theravada Buddhism also exists, as well as indigenous forms of Vietnamese Buddhism such as Bửu Sơn Kỳ Hương and Hòa Hảo.
There are conflicting theories regarding whether Buddhism first reached Vietnam during the 3rd or 2nd century BCE via delegations from India, or during the 1st or 2nd century from China. In either case, by the end of the 2nd century CE, Vietnam had developed into a major regional Mahayana Buddhist hub, centering on Luy Lâu in modern Bắc Ninh Province, northeast of the present-day capital city of Hanoi. Luy Lâu was the capital of the Han region of Jiaozhi and was a popular destination visited by many Indian Buddhist missionary monks en route to China. The monks followed the maritime trade route from the Indian subcontinent to China used by Indian traders. A number of Mahayana sutras and the āgamas were translated into Classical Chinese there, including the Sutra of Forty-two Chapters and the Anapanasati.
Jiaozhi was the birthplace of Buddhist missionary Kang Senghui, who was of Sogdian origin.
Over the next eighteen centuries, Vietnam and China shared many common features of cultural, philosophical and religious heritage as a result of geographical proximity and Vietnam being annexed twice by China. Vietnamese Buddhism is thus related to Chinese Buddhism in general, and to some extent reflects the formation of Chinese Buddhism after the Song dynasty. Meanwhile, in 875 new Cham king Indravarman II who was a devout Zen Buddhist, established Mahayana Buddhism as Champa's state religion, and built the large monastery complex of Đồng Dương.