Osun State occasionally known as the State of Osun by the state government, is a state in southwestern Nigeria; bounded to the east by Ekiti and Ondo states, to the north by Kwara State, to the south by Ogun State and to the west by Oyo State. Named for the River Osun—a vital river which flows through the state—the state was formed from the southeast of Oyo State on 27 August 1991 and has its capital as the city of Osogbo.