Land of Pines.
A great forested highland on the northern borders of Beleriand. Stretched for sixty leagues from west to east. On the northern and western sides were great pine forests. To the south it fell suddenly in dreadful precipices down to Doriath. From the northern slopes, Angrod and Aegnor overlooked the fields of Ard-galen.
Between Dorthonion and the Shadowy Mountains there was a narow vale, whose sheer walls were cald with pnes. The vale itself was green, for the river Sirion flowed through it towards Beleriand.
To the east was Himring, divided from Dorthonion by the the pass of Aglon.
Later called Taur-nu-Fuin.