Disaster / Destruction
For reasons unknown the continent fragments and the world changes.
In the afternoon of the 8th day of the new year, the land started to quake--everywhere. At first, many people around the world thought it was just a localized earthquake, but then the earthquakes lasted for a week, then a month, and then it had lasted 3 months. Towns and cities collapsed from the earthquakes, while some were swallowed whole by fissures that rent the ground asunder. As time passed, everyone realized that it was no local earthquake, as survivors of neighboring nations reported the same occurring in their nations, and their neighbors reporting the same also, and soon it was known that these tremendous earthquakes happened throughout the whole world. Then it was discovered that some nations had completely vanish, their locations replaced by the ocean. The land had fragmented, a once single super-continent that stretched across the world was split apart into smaller ones that were separated by seas and oceans.
Many claim that the Sundering was a punishment from the gods for the wrongdoings of mortals, some imagine that extremely powerful magic tore the land apart, and others posit that a collision with another plane is what caused the Sundering to happen. Ultimately, no one knows what caused such a cataclysmic event.