It's not a matter of getting things wrong. The history of the world as you know it is almost entirely fabricated.

[The whole world is lies, isn't that nice. He pauses for a moment to let that sink in before elaborating.]

Mithos and his companions did put an end to the great war, as I said. After the Great Tree withered, it left behind a seed, but this seed's mana was not enough to support the world. A massive amount of mana would be needed to revive the Great Tree, but the source of that mana, a comet called Derris Kharlan, wouldn't come close enough to the planet in order to supply that mana for several more decades. Mithos split the world in two as a means to conserve what little mana was produced by the seed. These worlds were named Tethe'alla and Sylvarant, after the two countries who had caused the war.

Before Derris Kharlan came close enough to supply the Great Seed with mana, a group of humans seeking to monopolize what little mana the seed produced attempted to take possession of it. During the conflict, one of Mithos' companions was killed; his sister, Martel.