Ya, It is true. J.R.R. Tolkien says that Ungoliant whent there and breded with the monsters there and had many ofsprings, some of them being the spiders of Mirkwood and of corse Shelob.
but it might not exist so how can she breed there its only speculation you know and i thik it might be on top of were utumno used to be cause it was destroyed before ungoliant was in the world
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His enemy halted again, facing him, and the shadow about it reached out like two vast wings.
… suddenly it drew itself up to a great height, and its wings were spread from wall to wall …
Nan Dungortheb (Valley of Dreadful Death) is the name of the wilderness south of Ered Gorgoroth and Dorthonion, east of Dimbar and the river Mindeb, west of Dor Dínen and the Esgalduin, and north of Neldoreth and Doriath. It is named after Ungoliant, who resided there after escaping the Balrogs of Morgoth and Lammoth. It is also named for its proximity to the Ered Gorgoroth, where Ungoliant's children haunted the deep vales of the mountains and its closeness to the shadowy webs of the Girdle of Melian.
I love those long names!
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Sing my world into being, Ainur. The universe needs your power!