Tai-Kadai Language Family

All members of the Tai-Kadai (also known as Kadai or Kam-Tai) language family evolved from an ancestral language called Proto-Tai which is thought to have originated in the area between northern Vietnam and southeastern China. Some 2,000 years ago, speakers of the Tai languages moved southward into Southeast Asia. Today, languages belonging to the Tai-Kadai language family are spoken by an estimated 85 million people in Southeast Asia in an area extending from Thailand into Laos, Vietnam, China, Burma, and India. The two national languages of the group, Thai and Lao, account for well over half the total of Tai-Kadai speakers. The spelling “Thai” is used for the national language of Thailand and for some regional varieties in that country. “Tai” is used for the wider Tai subfamily of Tai-Kadai and also in the names of some specific varieties.

According to Ethnologue, the Tai-Kadai family includes 76 languages. The distribution of the languages is very complex with much mapoverlapping and interpenetration of the languages. The total number of first-language speakers of Tai-Kadai languages is estimated to be around 85 million people. The largest number of speakers live in Thailand (around 45 million), followed by China with around 15 million. Smaller numbers live in other countries such as Vietnam, Assam, Burma, Laos, France, Europe, UK, U.S., and Canada.

The Tai-Kadai family is usually divided into three major branches, all of which are extraordinarily diverse:

  • Southwestern
  • Central
  • Northern

Some linguists consider the Southwestern and Central branches to be one.

70% of the 76 Tai-Kadai languages are spoken by fewer than 100,000 speakers. Of these, many are on the verge of extinction or are seriously endangered. A few are already extinct. Only 22 of the 76 languages have over 100,000 speakers, and only 9 have over 1 million speakers. Languages with over 100,000 speakers are listed below.

Sui 200,000 China
Cao Lan 187,000 Vietnam
Tai Daeng 165,000 Vietnam
Khün 121,000 Myanmar
Tai Dón 490,000 Vietnam
Dong Northern 463,000 China
Tai Nüa 357,000 China
500,000-1 million
Nung 856,000 Vietnam
Tai Dam 763,000 Vietnam
672,000 China
Hlai 667,000 China
Lingao 600,000 China
Phu Tai 519,000 Thailand
1 million and over
Thai 20 million Thailand
Thai Northeastern 15 million Thailand
Zhuang Northern 10 million China
Thai Northern 6 million Thailand
Zhuang Southern 4 million China
Shan 3.2 million Myanmar
Lao 3 million Laos
Bouyei 2 million China
Tày 1.5 million Vietnam



Only Thai and Lao are official languages of sovereign countries. Some of them, e.g., Gelao and Laha, are official nationalities in Vietnam and China respectively.


Sound system

The phonological systems of Tai-Kadai languages share some general features. Syllables consist of optional consonant(s) + vowel nucleus + optional final consonant(s) which are usually limited to nasals, semivowels, and final stops /p/, /t/, /k/, and glottal stop.


  • Tai-Kadai languages have a large number of vowels and diphthongs.
    Some languages, e.g., Thai and Lao, distinguish between short and long vowels.


Consonant systems are relatively simple. There are no consonant clusters. Only a few consonants can occur in syllable-final position.


All Tai-Kadai languages are tonal. Tone makes a difference in meaning so that many words in Tai-Kadai languages differ only in tone. The number of tones varies from three to nine.


There is a great diversity among Tai-Kadai languages in grammatical morphemes, such as particles and various grammatical markers. However, they all share some general features.


  • Nouns are not inflected for number, gender, or case. Such distinctions are assumed from context or are optionally indicated through special words or constructions.
  • Classifier constructions are used for counting and specifying objects.


Thai has a complex system of pronouns. The choice of pronouns in any given situation is determined by the sex, age, social position and the attitude of the speaker towards the addressee. Different pronouns are used in different situations.


Verbs are not inflected for person, number, tense, aspect, or mood. These functions are determined by context or by adverbs and expressions of time.

All Tai-Kadai languages have a wide range of particles. Among them are the following (as in Thai):

  • Politeness particles
    These are used to express deference towards the addressee. Polite language in Thai requires that a politeness marker be at the end of every phrase. The markers differ according to the gender of the speaker. Men will show deference by ending their questions and statements with khrahp to show respect and refinement. Women end their questions and statements with khah.
  • Mood particles
    These particles express the attitude of the speaker, such as urging, persuading, encouraging, etc.
  • Question particles
    Different question particles are used in yes-no questions, depending on whether or not the speaker has expectations as to what the answer may be.

Word order

Word order in Tai-Kadai languages varies depending on what is known and what is new information in the sentence. This means that Subject-Verb-Object, Subject-Object-Verb, and Object-Subject-Verb word orders are all possible. However, Subject-Verb-Object word order is considered to be the norm. Modifiers follow the nouns they modify.


Most words are monosyllabic, except for loanwords, compounds, and reduplications.
The lexicon of Tai-Kadai languages shows different influences. For more abstract and technical vocabulary the languages spoken in Vietnam and China rely on borrowings from Chinese. Languages to the west had borrowed from Sanskrit, Pali and Khmer.


Tai-Kadai languages in the southern and western areas, with long cultural connections to India, have been using syllabic Brahmi-based writing systems for over seven hundred years. Eight such scripts are currently in use. To the north and east, varieties in contact with Chinese once used modified character-based writing but romanizations have been recently introduced. Many languages in this family have never been written. Below are four examples:

Roman script Hlai
Lao script Lao
Thai script Thai
Shan script Shan


Language Difficulty
questionHow difficult is it to learn Tai-Kadai languages?
There is only data for Lao and Thai which are considered to be Category II languages in terms of difficulty for speakers of English.