Western Tirisfal Glades is the name used to refer the unnamed closed zone located to the west of Deathknell. At the game that zone is an inaccessible valley that appears on the map to be open-ended into the Silverpine Forest but is in fact fully enclosed by mountains. While clearly visible on the map, the valley has no name or other known purpose.
It has also been suggested as the location of the chamber occupied by Krasus, possibly created by the Highborne, building off the speculation this was their landing spot.
CataclysmThis section concerns content exclusive to Cataclysm.
On the World of Warcraft: Cataclysm map for Tirisfal Glades, this area has been replaced with mountains. In the actual world, that place now has a lake and trees accessible only by flying.