Cythral

Cythral, the Wildwood, is a realm of Athel Loren, ruled by Lady Draya the Nighthawk. Not all the spirits of Athel Loren dwell in harmony with the Elves. Even now, thousands of years after the first great council, there are those beings who actively seek the Elves’ destruction. Some revel in malevolence purely for its own sake, others would war against the Elves with all the cunning and might at their command, were they free to do so.

It was to guard against this threat that the first Wood Elves planted a fence of waystones in the southeast of Athel Loren, creating the Wildwood — a prison for the most malevolent of forest spirits. Thus can the Dryads and Treemen found elsewhere in Athel Loren, cruel as they are, be considered the most benign of their kind. Yet the waystone fence alone is not sufficient to indefinitely cage the creatures of the Wildwood. There are Treemen and other elemental colossi within, and their power is more than equal to the task of toppling a few menhirs. Losing one or two such stones has little effect on the cage’s efficacy, but if several adjacent waystones were felled, the breach would be enough to allow an escape.

It is the endless task of the Elves of the Wildwood to ensure that the waystones are maintained and thus the prison kept whole. They do not live in the Cythral itself, and indeed only enter it at times of great need, but instead maintain their halls on the outside of the waystone fence. No realm in all of Athel Loren is so unwelcoming of outsiders, and with good reason. Not all the creatures of the Wildwood are monstrous of form. Some are seductresses steeped in fey glamour, easily capable of luring mortals into their shadowy embrace. Few of such victims emerge from the Wildwood unharmed. Most of those that do are mortal creatures no more, their own souls having been devoured and replaced by those of shadow-naiads or deepwood fetchlings. The Rangers of the Wildwood must be ever on guard for such imposters, and so many outsiders are beheaded and burned for their trespassing. Better that the innocent perish than a changeling escape and insinuate itself into the courts of Athel Loren.

Source

 * Warhammer Armies: Wood Elves (8th Edition) -- pg. 12