The Grey Mountains, or the Ered Mithrin, was a large mountain range in Middle-earth located to the north of Rhovanion and south of Forodwaith.
History
The Grey Mountains were originally part of the Iron Mountains, the ancient mountain range in the north of Middle-earth, making them one of the oldest mountain ranges in Arda.
The mountains were mostly unaffected during the events of the First Age. At its future western end lay Mount Gundabad, where Durin I awoke.
After the War of Wrath, the Iron Mountains were broken, leaving the Grey Mountains as a separate range and a "northern spur" of the newer Misty Mountains.
In the year TA 2210 the mountains were settled by the Dwarves, led by King Thorin I. The mountains were rich in gold and unexplored, however after three hundred years Dragons began to trouble the Dwarves, killing Dáin I in TA 2589. His sons Thrór and Grór then abandoned the Grey Mountains, fleeing to Erebor and the Iron Hills.
Geography
The Grey Mountains were the last remnants of the wall of the Iron Mountains, which once stretched all over the north of Middle-earth, but were broken at the end of the First Age after the War of Wrath.
North of the mountains lay Forodwaith, a region of great cold known as Dor-na-Daerachas in the First Age and earlier. South of the mountains lay Rhovanion and Dale.
On the western end of the mountains, across a gap, lay Mount Gundabad, the end of the Misty Mountains. Halfway through its length, the mountains split, and the valley between them was known as the Withered Heath.
The stretch of mountains west of the Misty Mountains which still formed one range with the Grey Mountains was known as the Mountains of Angmar, another remnant of the Iron Mountains.
From east to west the mountains stretched some 350 Númenórean Miles. In its western end in Éothéod, the Forest River and the River Greylin arose.
Inhabitants
The Dwarves of Durin's Folk considered the Ered Mithrin as part of their land as far back as the reign of Durin I. Because of constant attack by both Orcs of Morgoth and possibly Dragons, they were not heavily explored or settled until the Third Age. By the end of the Third Age all Dwarven strongholds had been abandoned or raided by dragons, and the Grey Mountains served only to divide Forodwaith from Wilderland; during this period, the area was, according to Gandalf, "stiff with goblins, hobgoblins, and orcs of the worst description". Durin's Folk possibly reclaimed their halls in the Grey Mountains during the Fourth Age due to the dwindling of the Orcs and Dragons.
Etymology
The Grey Mountains are also known as Ered Mithrin in Sindarin; from ered (mountains) + mithrin (grey).