The great scholar William Gadney reckoned there were 80 or so living languages in what is called Thailand. Regionalism, provincialism and ethnicity determines many aspects of life. I, rather mournfully, encourage anyone interested in the country to read Siam Mapped by Thonhchai Winichakul. 1994 University of Hawaii Press. Thailand is an uneasy construct created, in the main, by force of arms in the first place and subsequently by Chinese immigration and the normal outposts of suppression.
The regions of Thailand, Lanna, based on Chiang Mai, Issan.. predominantly Lao but with multiple sub groups, Khmer leaning populations to the South East, Karen and Mon populations in the NW let alone the so called hill tribes of the Lisu, Akha, Hmong and the 'Malay' provinces which, again until the intervention of Britain were never part of the Thai Geobody, and there are 'Sea Gypsies' etc.
The prevailing ideology of the Thai monarchy and their supporters has been to create a notion of 'Thainess' which requires total devotion to the constructs of 'the monarchy', to the indivisibilty of 'Thai'territory, to some vague notion of 'being Thai'.
It has been a propaganda campaign of great success
Language, as everywhere, is crucial to this, though Gadney reckons Thai is a minority language after Lao and Teochew in the home. In Phuket and the South there are large communities speaking Passa Pak Thai, Hakka. About 5 million people speak Ligor dialect, spoken in Nakhon Si Thammarat, Phatthalung, Trang, Satun provinces and Mueang Pattani, Mae Lan, Khok Pho and Nong Chik Districts of Pattani Province.
Chaiya dialect, is spoken in Krabi, Phang Nga, Phuket, Ranong, Surat Thani and Chumphon Provinces.
Singora dialect, is spoken in Songkhla, Yala and mostly part of Pattani Provinces.
In Chiang Mai everyone spoke Passa Neua. In SanKhampaeng in Chiang Mai the road signs are bilingual Passa Neua and Thai.