I wonder if the common habit among the races of Tamriel hopping from landmass to landmass as the last sinks, crumbles, freezes, or burns could have some connection to the nature of Kulpas in Elder Scrolls. Time being depicted as a dragon or world serpent, maybe each Kulpa is its own land mass which has risen and sunken like the coils of a serpent as it wriggles through time.
All of these Kulpas which may have all taken place on the same Nirn, might have taken place across these land masses where inhabitants of each would spread to the next in the manner of “Stepping Sideways” that the Redguards write about. It may be less of a metaphysical stepping between dimensions, and more of just mass exodus onto a new landmass.