§ Of Beleriand and Its Realms The Silmarillion

In Ossiriand dwelt the Green-elves, in the protection of their rivers; for after Sirion Ulmo loved Gelion above all the waters of the western world. The woodcraft of the Elves of Ossiriand was such that a stranger might pass through their land from end to end and see none of them. They were clad in green in spring and summer, and the sound of their singing could be heard even across the waters of Gelion; wherefore the Noldor named that country Lindon, the land of music, and the mountains beyond they named Ered Lindon, for they first saw them from Ossiriand.