Kra-Dai, also known as Tai–Kadai, Daic, and Kadai, is a family of 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 respectively, whose speakers account for over half of the 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 Indic-based scripts. Others use Chinese character-based scripts, such as the Zhuang and Kam-Sui in southern China and surrounding regions. The government introduced Romanized scripts in the 1950s for the Zhuang and the Kam-Sui languages. Almost every 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 monosyllabic, but bisyllabic and multisyllabic 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.