Sons of Eorl
Dunlandish: Forgoil 'Straw-heads'
Location(s): The plains of Calenardhon west of Anduin and east of Isen
Title(s): Riders of the Mark
Dates: 2510 T.A. - F. A.
Parents: Descended from the Men of the Éothéod; also claim descent from Kings of Rhovanion.
Siblings: Akin to the Beornings and Woodmen of the west-eaves of Mirkwood
The Rohirrim are the people of Rohan:
[Cried Aragorn] ... "Many riders on swift steeds are coming towards us!"
[Said Legolas], "... Yellow is their hair, and bright are their spears. Their leader is very tall."
"I have been among them," [said] Aragorn. "They are proud and wilful, but they are true-hearted, generous in thought and deed; bold but not cruel; wise but unlearned, writing no books but singing many songs, after the manner of the children of Men before the Dark Years. ...
They have long been the friends of the people of Gondor, though they are not akin to them. It was in forgotten years long ago that Eorl the Young brought them out of the North, and their kinship is rather with the Bardings of Dale, and with the Beornings of the Wood, among whom may still be seen many men tall and fair, as are the Riders of Rohan..."
The Two Towers, LoTR Book 3, Ch 2, The Riders of Rohan
"But these Whiteskins [the Rohirrim] have better night-eyes than most Men, from all I've heard; and don't forget their horses! They can see the night-breeze, or so it's said." [Snarled by Uglúk, commander of the group of Saruman's Uruk-Hai that kidnapped Merry and Pippin.]
The Two Towers, LoTR Book 3, Ch 3, The Uruk-Hai
The Eotheod first came to the attention of Gondor during the reign of Calimehtar, which ended in 1936 T.A. Before this time they were a small remnant of the Northmen, descendents of the Men who had fought against Morgoth in the First Age. They were decimated by the Great Plague and were displaced and enslaved by the Wainriders during the reign of Narmacil.
Calimehtar, Narmacil's son, vowed to avenge his father's defeat and found ally in Marhwini of the North, who sent messages to Gondor warning of the strength of the Wainriders and the determination of the Northmen to revolt against their enslavement at the earliest opportunity. Calimehtar marched to Dagorlad and engaged the enemy while Marhwini's Eored attacked from behind. This was, in effect, the first alliance between Gondor and the Eotheod and it ended in the retreat of the Wainriders from the lands West of Morannon.
In 1944 T.A., the recovered forces of Rhun (the Wainriders) joined with the Southrons of Khand in a march upon Gondor. The Gondorrim and some number of Eotheod met them on the North Road of Ithilien, and Gondor's forces were routed. The King [Ondoher] and his first son [Artamir] were slain during the battle, and the Eotheod retreated. On counting their dead, they discovered the Prince Regent of Gondor, Faramir [last son of Ondoher], had disguised himself and ridden to battle with their forces against the will and knowledge of his father. This ended that house of the Kings of Gondor, and at this time Arvedui made his rejected bid for the crown. Shortly after this battle, the Eotheod retreated to the far north near the Misty Mountains and Mirkwood. Messages passed between the two peoples, but distance made close alliances impossible and a thousand years passed before the Eotheod again joined Gondor in battle.
Unfinished Tales, Part 3, Ch 2.3, Cirion and Eorl
The Eorlings, or the Rohirrim as they were called in Gondor, still used their own northern tongue; for the Riders of Rohan had come out of Éothéod near the sources of Anduin only some five hundred years before the days here spoken of [end of the Third Age]. Yet all but their humbler folk spoke also the Common Speech [Westron] after the manner of Gondor.
The Peoples of Middle-Earth, HoME Vol 12, Part 1, Ch 2, The Appendix on Languages
Rene, 1.23.03; Description & Language: Elena Tiriel 1.11.04, 1.18.04; meaning added by Loquacious 02.27.04; Forgoil: ET 4.16.04; Éothéod: ET 7.18.04; Sons of Eorl: ET 8.25.04