Age of Giants
According to Thrulnn the Lost, the Age of Giants was a time when all the world's giant races ruled Tyria. The norn, the jotun, and other giant races had magic the likes of which will never be seen again. The other races looked up to them, as they were superior to all these other races, and were gaining on the Six Human Gods. The Age of Giants ended when magic was stolen from them by the gods, confusing them and leading them to turn on one another. The norn turned to the Spirits of the Wild to redeem their strength and self-respect, whereas the jotun had no one and nothing to pull them from the quicksand.
Given the oral nature of the jotun's history-keeping since their civil war, and the scarcity of jotun historians (Thrulnn is credited as the last), the accuracy of this account of history cannot be confirmed. Furthermore, there are no other known historical accounts that corroborate this version of history.