Thung Si Udom is a district in the southwestern part of Ubon Ratchathani Province, northeastern Thailand. Neighbouring districts are (from the north clockwise): Det Udom, Nam Khun of Ubon Ratchathani Province and Kantharalak of Sisaket Province.
The minor district (king amphoe) Thung Si Udom was created on 1 April 1992, when six tambons were split off from Det Udom District. The inclusion of tambon Thung Thoeng into the new district was undone on 1 June 1993. The minor district was upgraded to a full district on 10 October 1997. The district is divided into five sub-districts (tambon), which are further subdivided into 52 villages (muban). There are no municipal (thesaban) areas, and five tambon administrative organizations (TAO).

Source: https://en.wikipedia.org/wiki/Thung_Si_Udom_District