To the northwest of Beleriand, protecting Hithlum on its eastern and southern borders
Sources
Eithel Sirion, the springs of Sirion, were in the eastern slopes of these Mountains, while Narog, Teiglin and Malduin rose from the southern part of the range
The mountain range of Ered Wethrin was so named because its towering peaks shut out the sun from the lands of Mithrim and Dor-lómin that lay in Hithlum to the north.