On October 10, 2004 - the town of Kamogawa, along with the town of Kayō (from Jōbō District), was merged to create the town of Kibichūō. The new town belongs to the newly created Kaga District, founded upon this merger.
On January 22, 2007 - the town of Takebe, along with the town of Seto (from Akaiwa District), was merged into the expanded city of Okayama. Mitsu District was dissolved as a result of this merger.