Shano fe Yula
The human plane had been untouched by outside influences. The gods had left it largely on its own, barring great calamity or pranks, and humanity developed with little issue. They had little reason to believe in anything beyond themselves and their gods in the sky, for surely they would have seen evidence of such in their hundreds of years of recorded history and magical development.
Then the elven plane collided with theirs.
In the aftermath of the Great Collision, there was an explosion of magical and technological development. The gods had given much magic to the elven lands, and now it could be readily shared with the humans. The collision of the planes unveiled the Planar Sea, the vast space surrounding them both, where all manner of spirits dwelled. For both cultures, it was a golden age.
Then the planes were separated once more.
The elven diaspora, now forever barred from returning home due to the vastness of the Planar Sea, gathered en masse around the few elven landmarks that remained. The booming industry of planar magic collapsed as many of its techniques were rendered useless. Portals all across the realms snapped closed and distorted their surroundings. Families were torn apart.
It has been many generations since the Great Division. Towns and kingdoms have been rebuilt and redesigned. Magic has begun the slow process of redeveloping technology. For the layman, life is fairly peaceful. But signs of the struggle remain. Necromancy, a forbidden form of Planar Magic, continues to grow. A demon is summoned in a northern city and is barely prevented from destroying it. Innocent folk vanish without a trace on the dangerous roads.
It is perhaps only a matter of time before chaos reigns once again.