Iyayun was the Reagent to the throne of Oyo after the demise of the fifth Alafin, Aganju. Iyayun was the daughter of the Onisambo, whose name was also Aganju. She was forcefully taken into Alafin’s custody during the war in which her father was captured. The war had started due to Iyayun’s father’s intransigence towards the Alafin’s marriage proposal to her.
Iyayun was pregnant with Kori, who eventually succeeded to the throne when Aganju died, and there was anxiety in the empire as Oduduwa’s dynasty was under the threat of been terminated, so the people of Oyo were thoroughly delighted when Iyayun had a son. Iyayun was allowed to rule as a full king in Oyo till her son Koro came of age. Aganju’s death is historically blamed on her revolting intimacy with Lugbe, son of the Alafin. A death sentence had been passed on Lugbe for this reason, and Aganju had suffered ill heath afterwards.