[sgxin]

Do you know the ancestors of Hainanese came from Fujian and Guangdong? they migrated there in the past 500 years….the native people there are similar to Malay. 

Their ancestors were mostly from Putian in Fujian province. You can tell the similarities between Hainanese and Hokkien dialects.

I believe Malay (polynesian) ancestor should be from Fujian-Zhejiang region and was displaced to Taiwan (where the aborigines have the purest Malay/Polynesian genes) when Han groups moved south.

But even if there were Malay ancestors who were originally in Hainan, they were probably displaced by the Li ethnic group many centuries ago.
The Li language is under the same family tree as Thai - e.g. The pronunciation for "Today" is similar to Thai "Wan ni" (video below).
I believe Hainanese also adopted some of the Li words as I just found out recently that the Laos pronunciation for chopsticks is very similar to Hainanese "Muey Du" !