Varn Campaign World
The epic party (Dibs, Ramzebak, Desc, et al) learned from Patang, guardian of the Brass Orb, that the plane of Varn was created (off of the Astral Plane) via the Genesis spell. There is always a planar guardian who continually expands and repairs the plane, over the centuries.
The first point created with the spell was the city of Ethras.
After a time (when?), the creators invited a community of elves (approx 700) to create and then live in the primordial forest, Vinyador. Other invitations followed suit, over the years.
Other communities came to the plane unbidden, in particular orcs and drow.
Construction on the plane ceased 1692 years after Genesis, or 553 YoH. Maintenance continues forever, though.