1) actually, since when was taiwan part of china?
when the europeans landed there 500 odd years ago, the islands were inhabited by alisan, supposedly the people the malays and polynesians originated from.
The europeans had to import chinese labour because the alisan were not the work disciplined types, sounds familair?
2) Most south east asian have the same cultural tread. the bow before passing in front of someone, never point with their fingers, using the thumbs instead, never raise their feet in front of people etc.... only difference is their language and religion. So i can only conclude that most south east asian came from the same region in southern china. they were probably chased out of their areas by the monggols or famine.