Hiroshima is a traditional center of the Chūgoku region and was the seat of the Mori clan until the Battle of Sekigahara.
On March 31, 2005, the towns of Hiwa, Kuchiwa, Saijo, Takano, and Tojo, from the former Hiba District (dissolved by this action) and the town of Souryo from the former Konu District (dissolved by this action) merged with the city of Shobara to create the new city of Shobara.