Rahim Yar Khan is the capital District as well as the tehsil of the same name. The city Rahim Yar Khan is one of the few cities in the world that are still at their pioneering places since the formation. It has been renamed customarily amid last 5000 years, first available (on record) name was AROR or ALOR and then it became City of Pattan, Phul Wada, Noshehra and now Rahim Yar Khan. It was declared as a separate administration district in 1943.
The district derives its name from its headquarter Rahim Yar Khan. The previous name of this district was Naushehra, which was built in 1875 A.D by Fazal Elahi Halani on the ruins of the ancient Pul-Wadda during the Sumra supremacy in Sindh. In the year 1881, the Railway Authorities desired to change the name of a railway station in the name of a town called Nowshera situated in Peshawar district. Consequently, in 1881 to avoid any confusion because of similar nomenclature Nawab Sadiq Khan-IV of Bahawalpur also changed the name of the sub-division Naushera after the name of his first son Rahim Yar Khan. Formerly, Rahim Yar Khan was also one of the names of the three districts of the former princely State of Bahawalpur until 1955. Today, it lies on an important train route which runs south to Sukkur and north to Bahawalpur.