Thailand is situated at the heart of Southeast Asia and as such, exhibits all the remarkable characteristics of the region, which is one the most complex areas of language and ethnicity in the world. The 70 languages of Thailand belong to five language families: Tai, Austroasiatic, Hmong-Mien, Sino-Tibetan, and Austronesian. All languages are hierarchically interrelated in Thai society with Standard Thai, the only official language, at the highest level. It is used as a medium of instruction in school and in the mass media all over the country. The ethnic minorities are in diglossic situations. They use their ethnic language at home and in their community and Standard Thai at school and on formal occasions.
With rapid changes to the ecology of language caused by global socioeconomics, modern culture, a powerful mass media, and a language policy which supports only the official language, as well as the negative attitude of the speakers towards their own language, ethnic minority languages are declining with the younger generation increasingly becoming monolingual in Standard Thai. At least fourteen languages are now endangered and may not be able to survive to the end of this century. Other languages, with the exception of Standard Thai, are also not safe.