sentences:  The eastern part of the district is in the Luang Prabang Range mountain area of the Thai highlands.The minor district ("king amphoe") was created on 20 June 1968, when the four "tambons", Puea, Chiang Klang, Chiang Khan, and Na Rai Luang, were split off from Thung Chang District.It was upgraded to a full district on 16 November 1971.