The Greatest of the Eldar

[Galin]

The Sindar are Eldar -- they were part of the Great March and reached Beleriand.

Eldar The Elves of the Great Journey out of the East to Beleriand.

List of Names , The Children of Húrin

'... and Eldar, the name of the Three Kindreds that sought for the Undying Realm and came there at the beginning of Days (save the Sindar only).' (RotK, Appendix F)

That's the short (fairly recent) version from Christopher Tolkien. And JRRT on Eldar according to The Lord of the Rings.