The Oyo Empire was not a hereditary monarchy, nor an absolute one. The Oyo Mesi selected the Alaafin. He was not always directly related to his predecessor, although he did have to be descended from Oranyan (also known as Oranmiyan), a son of Oduduwa (also known as Odudua, Odua ) and to hail from the Ona Isokun ward (which is one of the three royal wards).
The Oyo Mesi were seven principal councilors of the state. They constituted the Electoral Council and possessed legislative powers, similar to today's United States Congress. Led by the Bashorun, acting as prime minister, and ran by the Agbaakin, Samu, Alapini, Laguna, Akiniku and Ashipa.