Thailand’s official language is standard Thai, formerly known as Siamese, which is spoken by about 40 percent of the population. Thai is the predominant member of the Tai family of languages, which includes about 60 languages spoken throughout Southeast Asia. The Tai languages are difficult to place linguistically but usually are linked to either the Sino-Tibetan or Austronesian language families. Standard Thai is written in the Thai alphabet, derived from the Indian Devanagari script, and is characterized by the use of five tones. A strong Thai literary tradition goes back to the 13th century. Another 50 percent of Thailand’s population speak Tai languages other than Thai, such as Lao, spoken in the northeast. Most educated Thai speak English, and Chinese is also widely used. English, Chinese, and Japanese are often the languages of commerce. The Mon-Khmer family of languages is represented both among the hill peoples of the north and in lowland groups of Mon and Khmer peoples. Some Malay is spoken in the south.