Northern Thai (Thai: ภาษาไทยถิ่นเหนือ), also called Kam Mueang (Northern Thai: ᨣᩴᩤᨾᩮᩬᩥᨦ กำเมือง), Lanna or Tai Yuan, is the language spoken by the Northern Thai people of Thailand. It is a Southwestern Tai language. The language has approximately six million speakers, most of whom live in Northern Thailand, with a smaller community of speakers in northwestern Laos.
Speakers of this language generally consider the name "Tai Yuan" to be pejorative. They refer to themselves as Khon Mueang (ᨤᩫ᩠ᨶᨾᩮᩬᩥᨦ, คนเมือง, [kʰon˧.mɯaŋ˧] – literally "people of Mueang" meaning "city dwellers"), Lanna, or Northern Thai. The language is also sometimes referred to as Phayap (พายัพ, Thai pronunciation: [pʰāː.jáp]), "Northwestern (speech)".