Places in Middle-earth
Type: Kingdoms, Realms, Lands
Region: Beleriand & North
Meaning: Valley of Dreadful Death
[Ungoliant] went down into Beleriand, and dwelt beneath Ered Gorgoroth, in that dark valley that was after called Nan Dungortheb, the Valley of Dreadful Death, because of the horror that she bred there. For other foul creatures of spider form had dwelt there since the days of the delving of Angband, and she mated with them, and devoured them; and even after Ungoliant herself departed, and went whither she would into the forgotten south of the world, her offspring abode there and wove their hideous webs.
The Silmarillion, Quenta Silmarillion, Ch 9, Of the Flight of the Noldor
[That] region was filled with fear.... Thither, as was earlier told, Ungoliant had fled from the whips of the Balrogs, and there she dwelt a while, filling the ravines with her deadly gloom, and there still, when she had passed away, her foul offspring lurked and wove their evil nets; and the thin waters that spilled from Ered Gorgoroth were defiled, and perilous to drink, for the hearts of those that tasted them were filled with shadows of madness and despair. All living things else shunned that land, and the Noldor would pass through Nan Dungortheb only at great need....
The Silmarillion, Quenta Silmarillion, Ch 14, Of Beleriand and Its Realms
Elena Tiriel 28May04