They self identify as Thai though. To the point they consider being seen as Chinese as negative (according to them Chinese are dirty and rude).
Maybe it's because they are the 2nd, 3rd and 4th generation in Thailand and the Chinese that moved to Thailand were Buddhists just like the Thai.
Maybe it's because they are the 2nd, 3rd and 4th generation in Thailand and the Chinese that moved to Thailand were Buddhists just like the Thai.