The Grey Mountains were ruled by a kingdom of Dwarves, long ago, but the Dwarves were driven out by Scatha the Wyrm and other dragons. These mountains, according to legend, are where the Dragons who survived the War of Wrath came to dwell.
The lower slopes and foothills of this area are covered in evergreen forests. Further up, mountains of stone covered in snow. It snows here instead of raining, but snow does not accumulate beneath around y=140.
Orcs, Uruks, and Wargs of Mount Gundabad spawn here at night and can be encountered in any cave or structure.
Upon entering the Grey Mountains, the player earns the achievement "Here be Dragons?"
The Grey Mountains have one sub-biome, the Grey Mountains Foothills. The foothills are less mountainous than the actual Grey Mountains. The Foothills only spawn on the south side of the Mountains.
Variants
The entire biome is defined as a 'Mountains' biome and has the following variants:
Standard - Normal Grey Mountains biome.
Forest - Forest covered lands.
Light Forest - Lightly forested lands.
Aspen Forest - A forest dominated with aspen trees.
Maple Forest - A forest dominated with maple trees.
Larch Forest - A forest dominated with larch trees.
Two structures spawn here alongside scattered pillars and piles of stone and dwarven brick, and subterranean dungeons:
Ruined Dwarven Mine - Remnants of the time where Dwarves ruled the mountains. The mineshafts are rotted, raided, and broken, but at the bottom of the shaft one might find a dwarven forge or two.
Ruined Dwarven Tower - Another dwarven souvenir, but these appear to be handy bases for the local Gundabad Orc Chieftains and their bands of irregular troops. GundabadBanners mark these squatted buildings and they hold chests with Orc and some dwarven loot. Forges and crafting tables of both Orcish and Dwarven origin can also be found inside. These structures can be very useful for finding dwarven forges closer to the Misty Mountains, considering that mithril can only be smelted in a dwarven forge.
Mobs
The only mobs here are the creatures of Gundabad, except when Dwarves of the Iron Hills and Erebor invade.
Gundabad Orc - Orcs from Mount Gundabad allied only to themselves. They carry use scattered pieces of equipment and armour from various evil and neutral sets.
Gundabad Warg - Wargs (giant wolves) allied with the Gundabad Orcs.
Gundabad Uruk - Bigger, stronger, and meaner than the orcs of Gundabad, these Uruks are likely deserters from Mordor. They are very powerful, and good players are advised to avoid them.
Gundabad Uruk Archer - Gundabad Uruks armed with Orc Bows to pick off enemies from range.
Gundabad Warg rider - Gundabad orcs and archer rides the warg into battle.
Vegetation
Spruce, larch, fir and pine trees of various sizes grow in the common boreal valleys. The undergrowth is dominated by piles of needles. Only the hardiest of grasses manage to peek through the dense, acidic piles of needles covering the forested valley floors. Flowers are uncommon in this harsh, cold environment. No broadleaf trees are hardy enough to survive here. In the foothills, forests stretch for miles, with no mountains to interrupt the endless sea of trees.