From the introduction:
Long ago, Ashunera created the world, and the animals and plants that lived on it. The animals evolved over time into an animal-like people known as the Zunanma, and then split into two people, the Beorc, who lost these animal features, and the Laguz, who still retained them. They soon started to fight with each other over differences. Ashunera became upset and accidentally flooded the world with her emotions, save for the continent of Tellius.