Bjornaer Ancestral Quests

Anyone who's read the Bjornaer chapter in Mystery Cults know that they revere their ancestors, and the Clan Mysteries involve going on quests similar to the ones their ancestors did.
Do we know if these quests are indeed based on legends. And if so, is it possible to research any details? Where should I start? My Bjornear character's ancestor site is the Kerry Mountains in southern Iberia. Any legends about these that could be useful to look at?