Wiang Sa District, Nan

Wiang Sa (, ) is a district ("amphoe") in the central part of Nan Province, northern Thailand.
Geography.
Neighboring districts are, from the south clockwise, Na Noi of Nan Province, Rong Kwang, Song of Phrae Province, Ban Luang, Mueang Nan, Phu Phiang and Mae Charim of Nan Province. To the east it borders Xaignabouli Province of Laos.
The eastern part of the district is in the Luang Prabang Range mountain area of the Thai highlands.
History.
The minor district Mueang Sa was created in 1908, consisting of the seven "tambons" (sub-districts): Mueang Sa, Ai Na Lai, Ban San, Ban Khueng, Pong Sanuk, Nam Khao, and Lai Na split off from Mueang Nan District. In 1909 it was upgraded to a full district. In 1917 it was renamed Phun Yuen (บุญยืน), as the district office was in that tambon. In 1939 it was again renamed with its historical name, only leaving out the word "Mueang" which was reserved for the capital districts of provinces. The district was renamed Wiang Sa on 23 January 1986.
Administration.
Central administration.
Wiang Sa is divided into 17 sub-districts ("tambons"), which are further subdivided into 128 administrative villages ("mubans").
Local administration.
There are three sub-district municipalities ("thesaban tambons") in the district:
There are 13 sub-district administrative organizations (SAO) in the district: