During the middle ages, as the European populations expanded and encroached on the Fae realms, the Fae began to migrate. Some returned through portals to the Astral Realm to their home planes, while others spread across the earth and settled in hidden areas.
The realm of Faeland, is one plane or dimension where the nymphs dwell, in a place called Alara. The capital city of which is Misthaven.
Portals to Faeland exist in Antarctica, the Pacific Northwest (North America), and hidden places around the world. The fae realms are heavily guarded to keep earthlings out, but the fae do come through to mingle with those of their kind that remained on earth.
Many races dwell in Faeland and the other Astral Realms, including elves, dwarves, fairies, etc.