From the introduction:
Ancient lore states that Vana'diel was created as a playground for the Gods, who themselves were spawned from an enormous andsentient Crystal. For eons, the Gods joyfully played until eventually falling into a deep slumber. It was during this slumber that the children of the Gods rose and flourished in Vana'diel, extracting gold from stones, traveling through the sky, building mighty cities, and giving birth to grasslands across the world.
Eventually, the children longed to join their parents, and constructed a pathway to the Divine Entrance of Paradise. Enraged by such an insolent act, the Holy Gatekeeper smote the children, and cast their cities to the bottom of the sea.
Shortly thereafter, the Goddess Altana awoke, and saw the ruin that had once been Vana'diel. Filled with an emotion that the likes of a God had never felt before, sadness, Altana wept five divine tears. When the five tears fell upon the earth, they gave life to the five races of Vana'diel.