The wide plains of Talath Dirnen (The Guarded Plain) were the unoccupied lands in West Beleriand located between Nargothrond and Doriath above the River Narog.

Those plains were incessantly guarded by the people of Nargothrond, the followers of Finrod Felagund. The guards used the hill of Amon Ethir to keep watch over the plain.
Encyclopedia entry originally written by AinarielPalantir