The minor district (king amphoe) Tan Sum was created on 18 September 1978, when the three tambons  Tan Sum, Samrong, and Chik Thoeng were split off from Phibun Mangsahan district.
The minor district (king amphoe) Tan Sum came into existence on September 18, 1978, when the three tambons Tan Sum, Samrong, and Chik Thoeng were detached from Phibun Mangsahan district.