There are many planes in the macrocosm. Some are accessible only by the living, some only by the deceased. With that in mind, it is possible for sapient races can cross into other planes through portals (sapient races are races with souls, the life force of beasts is merely recycled). Here is a list of sapient (playable) races and their native planes:
Human: Aerekelo's favored children, humans are the most diverse of all the races. They dominate Novimus, though they share that plane with other sentient races.
Elf: Swithanne's favored children. They are virtually immortal, and possess wisdom and magic that other races cannot fathom. They hold dominion over Myriva.
Ixia: Plant people! They "rule" Agrison...kind of. It's weird.
Mer: Mer live "alongside" humans in the oceans of Novimus. This is an all female race, they can dwell on land, but only with the use of certain artifacts.