The Sindar were Telerin Elves who set out on the Great Journey to Aman, but who decided to remain on the western shores of Middle-earth in Beleriand.

They were originally composed of the Teleri who remained in Beleriand to search for their King, Elwë, and also of other Teleri who were persuaded to remain on the western shores of Middle-earth by Ossë.

The Laiquendi and the Nandor who came to Beleriand were also counted among the Sindar.

The Sindar were also referred to as the Grey-Elves, perhaps because they were neither Elves of the Light (Calaquendi) or of the Dark (Moriquendi), since they did answer the summons of the Valar but did not reach Aman. The term Grey-Elves may also be a reference to their High King Elwë, who had grey hair. The language of the Sindar is Sindarin.

The Sindar were split between two main countries - the realm of Doriath which was ruled by Thingol and Melian, and Falas under the lordship of Círdan the Shipwright.

In the third age of the Captivity of Melkor, evil things that had dwelt east of the Blue Mountains began to trouble the Sindar. At this time, they first considered the need for weapons and armour, which they had not needed before. They traded with the Dwarves of Nogrod and Belegost, and learned smithcraft from them. Thus armed, they drove the invading wolves and Orcs from their land and had peace again, for a time. The Sindarin Elves did not play a large role in the wars of the Noldor against Morgoth.

Although the Sindar had a deep love for Middle-earth, they could not be content once the desire of the sea awoke in them. As a result, many of the Sindar sailed into the West.
Encyclopedia entry originally written by Nanelleth