In 1792 Ubon Ratchathani became a province, and was also the administrative center of the monthon Isan. In 1925 it became part of monthon Nakhon Ratchasima, with the abolition of the monthon in 1933, the province became a first level subdivision of the country. Until 1972 Ubon Ratchathani Province was the largest province of Thailand by area. Yasothon Province was split off from Ubon Ratchathani Province in 1972, followed by Amnat Charoen Province in 1993.