Prismdale

In the Aeon of the Champion story series, Prismdale is the unofficial fairy kingdom. Not much about it has yet been revealed, other than the fact that it is located in a mystical realm out of sight and reach of most mortals (save for the unicorns of Equidar, their allies). Certain individuals can perceive ways into the realm that others cannot, and these have been notably concentrated in High Faerun, where there is a shrine to the Fairy Godmother.

The smurfs have not yet encountered this world, nor have they visited High Faerun, but they did know about the kingdom and its faefolk by interacting with some of the denizens who had entered Middle-Earth to bless its forests. Papa Smurf himself had some remarkable encounters with these faes during his youth, as part of his magic training.