The Girdle of Melian was an enchanted barrier surrounding the realm of Doriath throughout much of its existence, created by the Maia Melian. It enclosed the three forests of Neldoreth, Region, Nivrim and part of the land of Aelin-uial. All those who attempted to pass through it became enmeshed and wandered aimlessly as if lost in an impossible maze of trees, until they eventually perished.
Video: Milkymist & Edirol V4
Audio: Heavily stretched, phased, reversed, and remixed music from Bo Hansson's Lord of the Rings LP