Buddhism seems to have first arrived in Indonesia from south India and Sri Lanka. Later, Mahayana and Tantra liberally mixed with Hinduism became predominant. Buddhism's vigour, at least in Java, is attested by the great stupa of Borobordur built in the 9th century AD, one of the biggest religious edifices ever erected. But by the 13th century Buddhism had become corrupt and moribund and it faded away to be replaced by Islam. From the 1930's onward, monks from Sri Lanka and to a lesser degree Thailand, have had considerable success in introducing Theravada, and a rather syncretic type of Buddhism calling itself Buddhayana has also arisen. Mahayana is also present but is entirely confined to Chinese immigrants.