The Kings of Corco Modhruadh reigned over an area that was coextensive with the diocese of Kilfenora.
In the 12th-century, the kingdom split into Corco Modhruadh Iartharach ("Western Corcomroe") and Corco Modhruadh Oirthearach ("Eastern Corcomroe") also known as Boireann. These districts were ruled by the ÃÂ Conchubhair Corcomroe and ÃÂ Lochlainn families, respectively.
In the 16th-century these areas became the English administrative baronies of Corcomroe and Burren.
For further references, see Annals of Inisfallen