Golarion is Out of Balance!
In the year 4606 AR, the god Aroden died. Maybe his death was the signal of the end of humanity. 300 years later to the day in 4906 AR, all humans and all semi-humans disappeared off the face of Golarian without a trace and The Age of Lost Omens has given way to The Age of Imbalance. This event became known simply as “The Vanishing” and marked the starting point of the new Post Humanity Calendar. Since then distrust has broken out between the other sentient races of the planet, each blaming the other for the disappearance. After several great wars and large amounts of destruction, the races live as separately as possible, each in their own civilizations. Someone knows something is wrong and has drawn great heroes from across history to try and find the humans and return them to the world.
It has been over 800 years since “The Vanishing” and our heroes have appeared on Golarion. The last thing they remember is their deaths, and a strong pain in the head acts as a compass to lead them towards some unknown destination.