It is just a guess that the origin of the reigning name 'Iwakura' and 'Kogosho' is an address or demesne (land attached to a manor and retained by the owner for their own use), and the details are unknown.
「岩倉」「広御所」とも宮号の由来は居所か領地に縁があると推測されるのみで、詳細は未詳である。