There are three layers of mythology that shape cultural norms: deep mythology, addressable mythology, and the immediate world.
The first, the deep mythology, represents the myths and legends upon which the addressable mythology are based. These are references to gods and magic, to events which have happened so long ago as to be more allegorical in nature than representing actual events. In Earuth, the deep mythology represents events in Ear-du-roth, the events of Yune creating the Inferi, of the human race being cast out of the Garden, the many battles fought during the Time of War, and many of the events up until the Time of Heroes. There are only limited fragments of written materials that even capture these events and all oral histories have long since been lost.
The second, the addressable mythology, represents deeds and actions by individuals or groups which serve as examples of exalted or villainous behavior. Whereas the deep mythology helps to form core social and cultural beliefs (religious or otherwise), addressable mythology is equated more to legends than actual myths.
The final, the immediate world, represents the embodiment of addressable or deep mythology in individuals. In an example, someone might be compared to a legendary sword fighter and, as such, would be reminding everyone of that legend. Using the same example, that legendary sword fighter might have been thought to have embodied elements of specific Inferi which, in turn, roll up to the individual being compared and, as a consequence, force recollection of those myths and what they represent.
This interplay of myths to legends to actions is an extremely strong bond throughout the history of Earuth. We might even say that it is like the roots of the Great Tree in the Garden, connecting all of Earuth, across all the shards, together as a single world.