Umphang (, ) is the southernmost district (amphoe) of Tak province, Thailand, established by the Royal Decree Establishing Amphoe Umphang, BE 2502 (1959), which came into force on 6 May 1959. The district is on the Thai-Burmese border. It is also the name of the town center of the district. Neighboring districts are (north from clockwise): Phop Phra district; Khlong Lan district, and Pang Sila Thong district of Kamphaeng Phet province; Mae Wong district and Mae Poen district of Nakhon Sawan province; Ban Rai district of Uthai Thani province; and Thong Pha Phum district and Sangkhla Buri district of Kanchanaburi province. The western edge of the district has a long boundary with Burma. Surrounded by national parks and wildlife reserves, it is one of the least accessible districts in Thailand. Nevertheless, it has one major tourist attraction, Thi Lo Su Waterfall (น้ำตกทีลอซู), the largest waterfall in Thailand. History Umphang was established as a district in 1898. It was named Mae Klong (อำเภอแม่กลอง) back then and was part of Uthai Thani province. In 1906 it was renamed Umphang and moved to Kamphaeng Phet province. Its status was changed to a king amphoe and moved to Tak Province effective 1 January 1926. Finally in 1959 it was promoted back to district status. Etymology It was thought that the name Umphang came from Karen word Umpa, meaning the act of opening a bamboo container. This was performed by Burmese to show passports stored in the bamboo to Thai immigration officers. Geography Most of Umphang is mountainous, geographically separated from the east part of Tak Province by the Thanon Thongchai Range (ทิวเขาถนนธงชัย). In the southern part of Umphang are the Dawna Hills and the Thungyai Naresuan Wildlife Sanctuary while in the central part near Umphang town there is the Umphang Wildlife Sanctuary. Directly east of Umphang Wildlife Sanctuary is Mae Wong National Park (in Tak and Kamphaeng Phet Province) and Khlong Lan National Park (in Kamphaeng Phet Province). The area, due to its difficulty of access, was used as a base by the Communist Party of Thailand. An important river in Umphang is Mae Klong River (แม่น้ำแม่กลอง) which originates here and flows south into Kanchanaburi province. Climate Demographics A large number of the 28,000 population are hill tribes with Karen people making up the largest proportion. Karen were the original settlers here before Thais began to migrate into the area, and many place names