A historical term used to refer to the followers of Elu Thingol during the long years before the end of the First Age. These people were collectively known as the Sindar, the Grey-elves. The central forests of Beleriand formed Thingol's own Sindarin realm of Doriath, but the other Grey-elves throughout Beleriand, and along its borders, acknowledged his overlordship.

Until the breaking of Beleriand at the end of the First Age, all the Sindar lived west of the Blue Mountains. Most of the survivors of Beleriand's destruction settled in Lindon, but others passed eastward across Middle-earth (the ancestors of Legolas Greenleaf were among these). The term 'Sindar of Beleriand', then, refers back to the ancient times when all the Sindar dwelt together in the lands west of Ered Luin.