Known Facts
Some unknown singularity caused a global memory loss of all humanoid and demi-humanoid in the year 350 (Human Calendar).
The entire population of the continent Alyf found themselves unable to recall anything history and religion related. They stil knew their names, could recognize their family and knew about the skills they possessed, but could not remember anything that one could read in a history or religous book, like the political situation or the history of their ancestors.
The discovery that all libraries and spiritual places (like churches and temples) were burned down or otherwise destroyed and massive piles of burned literature and books inside and outside of cities caused great confusion, mass panics and several desperate theories that tried to explain the situation.
Today, 300 years later, stories of the Great Amnesia are mostly discarded as a legend or myth among the common folk while researchers and historians still attempt to make sense of their past.
Theories
The Church of the Narrator
See main article: Church of the Narration.
The Forgotten War Theory
This is the most common theory among the historians and by far the one with the most evidence. The theory proclaims, that there was a big war before. The fact that right after the amnesia, a lot of people proficient in battle and war strategy found themselves umemployed AND the countless graves of fallen soldiers near the west coast of the continent give historians enough evidence for this theory.
It is now known who fought against whom, but the graves are mixed with the remains of several species, so it is believed that it was not a racial war, but rather a political one.
What caused the end of the war, who won and lost and why the people wanted to forget about it by burning books and somehow wiping all memories of it is still unknown.
The Liar King and the Unpassable Sea
Shortly after the Great Amnesia took place, the current ruler of the Human Empire introduced new laws that made many people suspicious and even rebell. No one was allowed to cross the ocean in any direction; all war ships must be burned and none are allowed to be built; the military is reduced to a minimal capacity; and various other laws.
Of course, people disobeyed the orders and tried to crossed the ocean, but they either never returned or had no memories of what happened out there. The king was asked several times by advisors and visitors whether he knew more than the rest of his people, but he told everyone different stories and eventually stopped talking about the topic and put everyone in chains that asked too much.