Thai is the national and official language of Thailand and the mother tongue of the Thai people, Thailand’s dominant ethnic group. Thai is a member of the Tai group of the Tai-Kadai language family. The Tai-Kadai languages are thought to have originated in what is now southern China, and some linguists have proposed links to the Austroasiatic, Austronesian, or Sino-Tibetan language families. It is a tonal and analytic language. The combination of tonality, a complex orthography, relational markers and a distinctive phonology can make Thai difficult to learn for those who do not already speak a related language.