It was the third evening since they had fled from the Company, as far as they could tell: they had almost lost count of the hours during which they had climbed and laboured among the barren slopes and stones of the Emyn Muil, sometimes retracing their steps because they could find no way forward, sometimes discovering that they had wandered in a circle back to where they had been hours before.
–-Narrative of Frodo and Sam at the beginning of Book 4 in the Two Towers
The Emyn Muil (Sindarin for The Dreary Hills) biome is a barren, rocky, desolate place devoid of life. The sky is a dusty, depressing grey. This land once belonged to Gondor, but was forsaken when the power of Mordor grew and the fields of Calenardhon (now Rohan) were given to the Rohirrim. Great boulders rise like cathedral spires on the forsaken skyline. At night the area is crawling with Orcs of Mordor, making it an unsafe place for good players -- and even more so when Mordor decides to invade the place. And when you're busy watching out for Orcs, a Bandit is likely to come along and steal items from your inventory.
The Emyn Muil are an excellent location for a player base, as the jagged blocks that make up the biome can easily conceal a secret door. Players be warned, however: Bandits are more common here than anywhere else in Middle-Earth.
Upon entering the Emyn Muil you gain the achievement"A Nasty Drop".
The Eymn Muil feature the standard ore distribution, but unlike other biomes it also features hardened clay in patches on the surface. This would be useful for anyone interested in making large amounts of clay tiling, and it can be found in surface patches and in boulders across the biome.
In the Renewed versiononly, the hardened clay has been replaced by Granite as hardened clay was renamed to Terracotta in 1.12, which would not spawn naturally (whatever Mojang seem to think).
For the most part, the Emyn Muil are desolate, rocky hills, but there are small patches of green-brown grass in lower vales throughout the land. Sometimes, one can even find a oak tree growing among the rocks in this desolate place. Flowers do grow, albeit rarely, likely blotted out by the dusty grey sky and nutrient-poor scree soils.