That is contradictory with the southern area, Thais near border in the southern part are stern buddhist although they have contacts with muslim relatives and friends. Most of the South Thais, buddhist or muslim have Malay ancestry due to Sriwijaya conquest centuries ago. You can see that most of them are tanned skin people especially Thais in Songkhla, Saturn, and Nakorn Si Thammarat, resembling typical Malays. They may also have Indian ancestry and Arabian ancestry.
I'm the seventh generation of the Royal Southern Thai(Pattani) who migrated to Kelantan after being chased by the Siamese Kingdom. I'm not so clear about the history. I have a book about our history which was written in Jawi. Very small Jawi and very classic language, I was impatient to finish it. all the ladies carries name Naan and the men will use Long. My grandma uses Naan before her name. She married to my grandpa who is a normal people, so my dad and his siblings have to use Che' instead of Long before their name. My brothers from father's previous marriage uses Che'. My siblings and I, do not use it.
I don't really understand the history since we never mix with our second cousins our our fathers's cousins. The thing that I know is that they are very protocol and they use royal language, which my mom don't like it.
I only know that they lost the battle, and left for Kelantan. Their white elephant died somewhere in Pasir Puteh. They ran to Manir, Terengganu and settled there. The princess name was Naan Cayang. We cannot eat the big bamboo shoot(rebung buluh betung) since there was a spell to us if we consume it. One of the relative ate it and fell sick then he died. If I'm not mistaken he is just 2 generation up. The spell is until 7th generation and I am the 7th generation.