This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Linguistics. Please check back later for the full article.
Kra–Dai, also known as Tai–Kadai, Daic, and Kadai, are a family of highly diverse languages found in southern China, northeast India, and Southeast Asia. The number of these languages is estimated to be close to a hundred, with approximately 100 million speakers all over the world. As the name itself suggests, Kra-Dai is made up of two major groups, Kra and Dai. The former refers to a number of lesser-known languages, some of which have only a few hundred fluent speakers or even less. The latter (also known as Tai, or Kam-Tai) is well established, and comprises the best known members of the family: Thai and Lao, the national languages of Thailand and Laos, whose speakers account for over half of Kra-Dai population.
The ultimate genetic affiliation of Kra-Dai remains controversial, although a consensus among Western scholars holds that it belongs under Austronesian. The majority of Kra-Dai languages have no writing systems of their own, particularly Kra. Languages with writing systems include Thai, Lao, Sipsongpanna Dai, and Tai Lue. These use the Indic-based scripts. Others use Chinese character-based scripts, such as the Zhuang and Kam-Sui in southern China and surrounding regions. Romanized scripts were also introduced in the 1950s, by the government for the Zhuang and the Kam-Sui languages. Almost each group within Kra-Dai has a rich oral history tradition.
The languages are typically tonal, isolating, and analytic, lacking in inflectional morphology, with no distinction for number and gender. A significant number of basic vocabulary items are mono-syllabic, but bi-syllabic and multi-syllabic compounds also abound. There are morphological processes in which etymologically related words manifest themselves in groups through tonal, initial, or vowel alternations. Reduplication is a salient word formation mechanism. In syntax, the Kra-Dai languages can be said to have basic SVO word order. They possess a rich system of noun classifiers. Other features include verb serialization without overt marking to indicate grammatical relations. A number of lexical items (mostly verbs) may function as grammatical morphemes in syntactic operations. Temporal and aspectual meanings are expressed through tense-aspect markers typically derived from verbs, while mood and modality are conveyed via a rich array of discourse particles.