Southern Thailand
Starting in peninsular Southern Thailand, the folks down there are ethnically Malay mostly. The language is different: Pak Thai. Folks speak a different dialect.
The food tends toward the very spicy. It's where most of the coconut groves are, where the stuff like coconut cream and products that come from coconut originate. There tends to be some very thick, rich coconut curries down there. There is a lot of seafood. The staple rice there is jasmine rice.
A typical dish down there might be something called kaeng tai pla, which is a very, very spicy curry made from fish stomach. It has got a little bitter element to it.