There is disagreement on when exactly Buddhism arrived in Vietnam. Buddhism may have arrived as early as the 3rd or 2nd century BCE via India, or alternatively during the 1st or 2nd century from China. Whatever the case, Mahayana Buddhism had been established by the second century CE in Vietnam. By the 9th century, both Pure Land and Thien (Zen) were major Vietnamese Buddhist schools. In the southern Kingdom of Champa, Hinduism, Theravada, and Mahayana were all practiced until the 15th century, when an invasion from the north led to the dominance of Chinese-based forms of Buddhism. However Theravada Buddhism continues to exist in the south of Vietnam. Vietnamese Buddhism is thus very similar to Chinese Buddhism and to some extent reflects the structure of Chinese Buddhism after the Song Dynasty. Vietnamese Buddhism also has a symbiotic relationship with Taoism, Chinese spirituality and the native Vietnamese religion.