sentences:  The sub-district is on the Kok River near the border with Myanmar, about a three hour drive north of Chiang Mai.The central village of the subdistrict is "Ban Tha Ton".The river forms part of the border and consequently the village has changed hands numerous times in the turbulent history of the area with the latest change happening in the early-20th century when the border was moved 3.2 km upstream leaving the north bank, previously part of Burma (Myanmar), to Thailand.