§ Of Beren and Lúthien The Silmarillion

It is told in the Lay of Leithian that Beren passed through Doriath unhindered, and came at length to the region of the Twilight Meres, and the Fens of Sirion; and leaving Thingol's land he climbed the hills above the Falls of Sirion, where the river plunged underground with great noise. Thence he looked westward, and through the mist and rains that lay upon those hills he saw Talath Dirnen, the Guarded Plain, stretching between Sirion and Narog; and beyond he descried afar the highlands of Taur-en-Faroth that rose above Nargothrond. And being destitute, without hope or counsel, he turned his feet thither.