The earth rumbled and shake, buildings and houses collapsed, screams of the people echoed across the land and sea. The world was ending, except it wasn't, mother nature had enough of mankind and tried to revert back into its original form, only a chunk of land covered by blue water. Many people died tragic deaths and the supercontinent would be later called "The United Lands" or some people call it "Pangea".
After the earthquake ended demons escaped from the netherworld and terrorized the land, a war began between men and demons. Humanity was losing but then a group of people who had abilities awaken from within their bodies and were known to be stronger than the demons and successfully slain their leader.
After many years passed by it was later known as "The Union" and was always celebrated as a memorial for the people who died in the war, but then suspicion against the people who have abilities rose, and why only those people have it.
The humans got to a conclusion that these people are actually demons and started a war with them, the humans that got abilities were outnumbered by the humans, the humans that got abilities lost hope but fought back to clean their names but then when people thought that only two sides were having a war, the demons rose up and tried to do what they tried to do before. They came back stronger and threatened to wipe humanity including the humans that got abilities, but the humans and the people who got abilities joined forces and successfully got their victory.
After proving that they were still humans even with their abilities, humanities accepted them and built a peaceful community.