A link between eras.

swords clashed, the end of the world came, many went through the portal, and some hid under the ground. The portal collapsed, and life on the surface became impossible. And everyone was forced to live underground.

So, the action takes place in Enroth? In principle, I had an idea to avoid unnecessary clutter of worlds. :) Then the similarity of the world in all its manifestations becomes clear. Then it should be that not everyone hid underground, but only part of the elves. Part of the people, led by Robert Falcon, boarded ships and sailed to the southern islands, where, with the support of angels, they were able to survive the nuclear winter.