A world trying to rebuild itself after the end of the world happened overnight

The Lost Age of The Ancients/The Age of Gods
None is known of this lost age but vague myths and legends of powerful beings doing great things. Before Rigenwald, once every few centuries a ruin from this age would be discovered. But since the calamity, those who knew anything were lost; dead or gone, no one body.

The Age of Chaos
The dawn of sentient species. Millennia pass as they struggle to control nature. A dark reminder that nature is powerful.

The Age of Settling
Man creates larger settlements and begins to expand. Colonies, Kingdoms, and Empires begin to rise. Nature fights back, but man is stronger.

The Age of Order
Large Empires and Kingdoms have risen. Nature is on it's last leg as the men of this world siphon off any resource wherever they find it, be it deep inside the jungles or down below the mountains. Borders expand. Wars are waged. Kingdoms and Empires fall. Technology is rapidly progressing.

Rigenwald
The 10th of December 846, all nations fell overnight. Cities and castles crumbled to the ground. Millions of people died, and not a single living person knows what happened. Nature creeps back...

The Age of Calamity
After Rigenwald, chaos reigned once again. The remaining people were forced to band together regardless of race. Some became scavengers. Some became bandits. Others tried to become settlers. Some succeeded. Others died trying. Nature aggressively takes back what is rightfully hers. Racial grudges slowly disappeared as they realized they were all going to be fucked.

The Age of Mending
Two centuries after Rigenwald, people are beginning to stabilize once again. Larger communities grow in the ruins of the old cities, but nature is still fighting back. People are once again exploring the world, or at least whatever remains of the old one. Following myths, legends, and rumors, our heroes are one of the first to explore whatever remains of the old world in the region of Allestro to find riches and glory.

It is the 4th of September 226 AR (After Rigenwald). Our heroes are in resting outside the ruins of Northern Baruïn after a weeks travel from Dykara; following the rumors of a large treasure cache and something else...