Far and wide [Shelob's] lesser broods, bastards of the miserable mates, her own offspring, that she slew, spread from glen to glen, from the Ephel Dúath to the eastern hills, to Dol Guldur and the fastnesses of Mirkwood.
”
–The Two Towers, Shelob's Lair
Nan Ungol (Sindarin: Valley of Spiders) is located in the southwest corner of Mordor. Nan Ungol is like the rest of Mordor, except for the webs of Ungoliant scattered around, the evil Mordor spiders, and the increased wildness of the biome. The land is dark, the terrain composing of Mordor Rock, and the sky is darkened by the ash and dust coming from Mount Doom, protecting the orcs from the sun and allowing them to spawn at any point in the day. Mordor spiders also spawn and can be hired from Mordor Orc spider keepers. It's definitely not a good idea to enter Mordor through this side of the country, but if you're geared enough, this region can give a huge alignment bonus, because killing spiders gives you alignment, and the spiders are indeed plentiful...
Upon entering Nan Ungol, the player earns the achievementThe Spawn of Ungoliant
Mordor Orcs - Evil Orcs of Mordor, equipped with Mordor armour, and armed with Mordor weapons, such as scimitars, spears, battleaxes, daggers, warscythes, or warhammers. They can also be found riding Spiders.
Mordor Orc Bombardiers - Mordor Orcs with Orc bombs. They are very destructive, and when the bomb has been used, the Bombardier will switch to a dagger. Hired bombardiers can be re-equipped with new bombs.
Three ores are exclusive to Mordor, although no other ores spawn here as Mordor is made of Mordor rock. Durnaur ore spawns here, and is used for Orc torches among other uses. Morgul iron ore is exclusive to Mordor, Angmar, and Dol Guldur, and can be smelted into Orc steel ingots; Nan Ungol is a very good place to find Morgul Iron because of how low in elevation it is, which makes it easy to travel around and mine the ore from the ground if you are short on Orc steel ingots. Gulduril ore also spawns here, and is used (among other uses) for making Morgul portals back to the Overworld.
Vegetation
Only a few plants grow in Nan Ungol. There are charred trees scattered about the landscape. Thorns and withered moss spawn here as well. Morgul-shrooms also spawn, albeit only in Orc camps.