Hinduism spread far and wide in ancient times to almost all of Southeast Asia and areas like Afghanistan. There is much evidence of strong Hindu traditions and ties to India in these countries from temples like Angkor Wat to influences in language and scripts. At some point the Thais, Khmer, Burmese, Malays, Javanese, Filipinos, and Champa of Vietnam were all Hindu. So why did every country convert away from it? Now all these countries practice Islam, Buddhism, and Christianity. Even close places to India like Sri Lanka and Bangladesh are Buddhist or Islamic. Why was Hinduism so strong and then it never stuck around?