A Brief History of Rohan
For good reason are the Rohirrim called the Men of the North. They had been the Éothéod, the Horse People, dwelling far to the North, lovers of the plains, delighting in horses and in all feats of horsemanship. There had been a long friendship existing between the Éothéod and the Men of Gondor. In the days of Eorl, in the year 2510 of the Third Age, some five hundred years before the War of the Ring, a peril threatened Gondor, danger from both the wild men of the Northeast and orcs out of the Mountains, and Cirion, Steward of Gondor, sent north for help. News came late to Eorl, but he determined to ride to the aid of Gondor nonetheless. All hope was lost in Gondor when, unlooked for, the Riders came out of the North, and great was the fear that went before the horseman of the North. Gondor was saved. In reward for their aid, Cirion gave the land of Calenardhon to Eorl and his people, and they settled it. They named it anew the Mark of the Riders, and they called themselves the Eorlingas; but in Gondor their land was called Rohan, and its people the Rohirrim (that is, the Horse-lords). Thus Eorl became the first King of the Mark. There the Rohirrim lived afterwards as free men under their own kings and laws, but in perpetual alliance with Gondor.
Thengel, Théoden's father, married Morwen of Lossarnach in Gondor, for he had lived long in Gondor before his father Fengel died, and when he became King of the Mark, the speech of Gondor was used in his house. Of his three children, Théoden was his only son, and Théodwyn, the youngest daughter, was much beloved by Théoden. Théoden became king in 2980 upon the death of Thengel, and in 2989 Théodwyn married Éomund of Eastfold, the chief marshal of the Mark. Her son Éomer was born in 2991 and her daughter Éowyn in 2995. Éomund was slain by orcs in 3002, and not long after Théodwyn took sick and died to the great grief of the king. Her children he took into his house, calling them son and daughter. He had only one child of his own, Théodred his son, then twenty-four years old; for the queen Elfhild had died in childbirth and Théoden did not wed again. Éomer and Éowyn grew up at Edoras and saw the dark shadow fall upon the halls of Théoden. The War of the Ring and the death of Théoden were in the year 3019 of the Third Age.