 Originally named Phimun Mangsahan (พิมูลมังสาหาร), it was renamed to Phibun Mangsahan on 30 July 1940.Phibun Mangsahan is divided into 14 sub-districts ("tambons"), which are further subdivided into 180 administrative villages ("mubans").Missing numbers belong to "tambon" which now form Sirindhorn District.