Thai (Thai: ภาษาไทย, transcription: phasa thai) is the national language of Thailand, spoken by around eighty percent of the sixty million residents of the South-East Asian country. Linguists consider it an "uninflected, primarily monosyllabic, tonal language" in the "Ka-Tai group." The spoken language is believed to have originated in the area which is now the border between Vietnam and China, an idea which provides clues to the origin of the Thai people, an area of continued scholarly debate. Linguistically, the language is related to languages spoken in eastern Burma, northern Vietnam, Yunnan, and Laos.
The written Thai Language was introduced by the third Sukothai period king, Ramkamhaeng, in 1283. This writing system has undergone little change since its introduction, so inscriptions from the Sukothai era can be read by modern Thai readers. The writing was based on Pali, Sanskrit, and Indian concepts, and many Mon and Khmer words entered the language.
Within Thailand, there are four major dialects, corresponding to the southern, northern ("Yuan"), northeastern (close to Lao language), and central regions of the country; the latter is called Central Thai or Bangkok Thai and is taught in all schools, is used for most television broadcasts, and is widely understood in all regions. Nowadays, English is also taught in all public schools. There are a few minor Thai dialects such as Phuan and Lue, spoken by small populations. Also within Thailand, small ethnic minority groups (including so-called "hill tribes") account for around sixty languages which are not considered related to Thai.
The four primary dialects of Thai should not be confused with four different "languages" used by Thais in different social circumstances. For example, certain words are used only by Thai royalty, creating a royal language. There are also languages used for religious figures, polite everyday interactions, and gruff or crude communications.