§ Of the Ruin of Doriath The Silmarillion

Thus it came to .pass that when the Dwarves of Nogrod, returning from Menegroth with diminished host, came again to Sarn Athrad, they were assailed by unseen enemies; for as they climbed up Gelion's banks burdened with the spoils of Doriath, suddenly all the woods were filled with the sound of elven-horns, and shafts sped upon them from every side. There very many of the Dwarves were slain in the first onset; but some escaping from the ambush held together, and fled eastwards towards the mountains. And as they climbed the long slopes beneath Mount Dolmed there came forth the Shepherds of the Trees, and they drove the Dwarves into the shadowy woods of Ered Lindon: whence, it is said, came never one to climb the high passes that led to their homes.