Chiang Muan District is a district (amphoe) in the southern part of Phayao Province, northern Thailand. Chiang Muan was originally part of the District Ban Muang of Chiang Rai Province (which was later renamed Pong District). On 12 May 1969, the minor district (king amphoe) Chiang Muan was established as a subordinate of Pong district, consisting of the two tambons Chiang Muan and Sa. The third sub-district Ban Mang was established in 1970. On 1 April 1974, it was upgraded to a full district and, in 1977, it was added to newly established Phayao Province.
Neighbouring districts are (from the west clockwise): Dok Khamtai and Pong of Phayao Province; Ban Luang of Nan Province; and Song of Phrae Province. The Phi Pan Nam Mountains dominate the landscape of the district. The Yom River, which has its sources in the range, is an important water resource. Doi Phu Nang National Park is in Chiang Muan District.
Chiang Muan is divided into three sub-districts (tambons), which are further subdivided into 34 administrative villages (mubans).

Source: Wikipedia