The Iraqi province of Diyala lies to the north of Baghdad. Its shares its eastern border with Iran, its northern border with Kurdistan, and its western border is shaped by the flow of the Tigris River. The Diyala River, a tributary of the Tigris, flows south through Diyala before meeting with the Tigris just south of Baghdad. Diyala's main cities include Baqubah (its capital), Muqdadiyah, Balad Ruz, Khalis, and Khanaqin. The province has a mix of Sunni Arab, Shi'a, and Kurdish residents.