Mount Hyjal does not require attunement. Prior to Patch 2.4 completion of File:Neutral 15.png [70] The Vials of Eternity was needed in order to enter the instance. The quest is still in the game, the only substantial reward being the Band of Eternity set of rings. Prior to patch 3.0.2 completion of the quest chain also rewarded the "Hand of A'dal", which now is no longer available.