Speakers of this language generally consider the name "Tai Yuan" to be pejorative[citation needed].

The use of the Tua Mueang, as the traditional alphabet is known, is now largely limited to Buddhist temples, where many old sermon manuscripts are still in active use.

There is no active production of literature in the traditional alphabet, and when used in writing standard Thai script is invariably used.

There is a resurgence of interest in writing it in the traditional way, but the modern pronunciation differs from that prescribed in spelling rules.

All Southwestern Tai languages form a coherent dialect continuum of more or less mutually intelligible varieties, with few sharp dividing lines.

The ancestors of the Northern Thai people were speakers of Southwestern Tai dialects that migrated from what is now southeastern China, specifically what is now Guangxi and northern Vietnam where the diversity of various Tai languages suggests an Urheimat.

[3] Due to the influx of Han Chinese soldiers and settlers, the end of the Chinese occupation of Vietnam, the fall of Jiaozhi and turbulence associated with the decline and fall of the Tang dynasty led some of the Tai peoples speaking Southwestern Tai to flee into Southeast Asia, with the small-scale migration mainly taking place between the eighth and twelfth centuries.

They settled in areas adjacent to the kingdom of Hariphunchai, coming into contact with Mon-speaking people whose writing system was eventually adapted for the Northern Thai language as the Tai Tham script.

[5] In the 13th century, King Mangrai consolidated control of these territories, establishing the kingdom of Lan Na.

In the 15th century, King Tilokkarat ushered in a golden age for Northern Thai literature, with a profusion of palm leaf manuscripts written in Tai Tham, using vernacular Northern Thai and interspersed with Pali and Buddhist Indic vocabulary.

[6][5] In 1775, Kawila of Lampang revolted with Siamese assistance, and captured the city, ending 200 years of Burmese rule.

In 1899, Siam annexed the Northern Thai principalities, effectively dissolving their status as sovereign tributary states.

[8] Thanajirawat (2018)[9] classifies Tai Yuan into five major dialect groups based on tonal split and merger patterns.

The top entry in every cell is the symbol from the International Phonetic Alphabet, the second entry gives the spelling in the Thai alphabet, where a dash (–) indicates the position of the initial consonant after which the vowel is pronounced.

The vowels each exist in long-short pairs: these are distinct phonemes forming unrelated words in Northern Thai,[14] but usually transliterated the same: เขา (khao) means "they/them", while ขาว (khao) means "white".

For purposes of determining tone, those marked with an asterisk are sometimes classified as long: Additionally, there are three triphthongs, For purposes of determining tone, those marked with an asterisk are sometimes classified as long: The following section largely concerns the Nan dialect of Northern Thai.

[15] (Tai Tham script) (Thai script) There are six phonemic tones in the Chiang Mai dialect of Northern Thai: low-rising, low-falling, high-level with glottal closure, mid-level, high-falling, and high-rising.

Sources have not agreed on the phonetic realization of the six tones in the Chiang Mai dialect.

The passive voice is indicated by the insertion of ᨯᩰ᩠ᨶ / โดน (don, [dōːn]) before the verb.

Such tonal mergence ambiguity is avoided when the language is written with the Northern Thai script.

It also depends on the initial consonant, as can be seen from the merged Gedney tone boxes for Standard Thai and the accent of Chiang Mai: Note that the commonalities between columns are features of the Chiang Mai accent.

However, it also serves as a summary of the rules for tone indication when the writing system is essentially etymological in that regard, as is the case with the major Tai-language writing systems using the Thai, Lanna, New Tai Lue, Lao and Tai Dam scripts.