That would apply to regions that were never colonized or claimed by anyone. For example, D'Hara claiming to Desert of Silouhettes, and making deals with people to have them all recognize this to put pressure on everyone else to not contest the claim.
Denmyask, though? It seemed pretty obvious the Astrum colony would want it. And Asylon saying "sure, you can have it" doesn't really mean squat as they obviously don't hold any authority over it.
Previous occupation of the region is just a greater reason to seek OTHERS to ratify your own claim in order to challenge the logical claim of the successor realm.
