§ Of the Sindar The Silmarillion

Now as has been told, one Lenwë of the host of Olwë forsook the march of the Eldar at that time when the Teleri were halted by the shores of the Great River upon the borders of the westlands of Middle-earth. Little is known of the wanderings of the Nandor, whom he led away down Anduin: some, it is said, dwelt age-long in the woods of the Vale of the Great River, some came at last to its mouths and there dwelt by the Sea, and yet others passing by Ered Nimrais, the White Mountains, came north again and entered the wilderness of Eriador between Ered Luin and the far Mountains of Mist. Now these were a woodland people and had no weapons of steel, and the coming of the fell beasts of the North filled them with great fear, as the Naugrim declared to King Thingol in Menegroth. Therefore Denethor, the son of Lenwë, hearing rumour of the might of Thingol and his majesty, and of the peace of his realm, gathered such host of his scattered people as he could, and led them over the mountains into Beleriand. There they were welcomed by Thingol, as kin long lost that return, and they dwelt in Ossiriand, the Land of Seven Rivers.