<P> In the third century B.C., there was disagreement among Ceylonese monks about the differences in practices between some councils of Bhikkhu monks and Vajjian Monks . The Bhikkhu monks affirmed Theravada traditions and rejected some of the practices of the Vajjian monks . It is thought that this sparked the split between Theravada and Mahayana Buddhism . </P> <P> Theravada Buddhism was formed and developed by Ceylon Bhikkhus during a period spanning from the third century B.C. to fifth century A.D. Ceylonese influence, however, did not reach Southeast Asia until the eleventh century A.D. Theravada Buddhism developed in Southern India and then traveled through Sri Lanka, Burma, and into Thailand, Cambodia, Laos and Beyond . </P> <P> In the twelfth Mahayana Buddhism developed in Northern India and traveled through Tibet, China and into Vietnam, Indonesia and beyond . </P> <P> Buddhism is thought to have entered Southeast Asia from trade with India, China and Sri Lanka during the 1st, 2nd and 3rd centuries . One of the earliest accounts of Buddhism in Southeast Asia was of a Theravada Buddhist mission sent by the Indian emperor Ashoka to modern - day Burma in 250 BCE . The mission was received by the Mon kingdom and many people were converted to Buddhism . Via this early encounter with Buddhism, as well as others due to the continuous regional trade between Southeast Asia, China and South Asia, Buddhism spread throughout Southeast Asia . After the initial arrival in modern - day Burma, Buddhism spread throughout mainland Southeast Asia and into the islands of modern - day Malaysia and Indonesia . There are two primary forms of Buddhism found in Southeast Asia, Theravada and Mahayana . Theravada Buddhism spread from India to Sri Lanka then into the region as outlined above, and primarily took hold in the modern states of Burma, Cambodia, Laos, Thailand and southern Vietnam . Mahayana Buddhism is thought to have spread from both China and India during the first and second century into Southeast Asia . Mahayana took root primarily in maritime Southeast Asia, although there was also a strong influence in Vietnam, in part due to their connection with China . </P>

Became the dominant sect of buddhism in southern india sri lanka and mainland southeast asia