These horses were among the most noble of the Endorian beasts. They had been unknown as a breed before ca. T.A. 2545, the approximate date that the first breeding herd was fully established in Rohan by Eorl the Young. However, individual Mearas were to be found in Middle-earth before that date, especially on the far plains of southern Rhovanion. They were commonly (and correctly) believed to be the descendants of Nahar, the Steed of Oromë, as were the Elf-horses. The progenitor of the breed of mearas in Rohan was Felaróf, who was white. Such was his strength as an ancestor that most of his descendants were white or dappled gray. All mearas, regardless of their color, shared Felaróf's other characteristics. They understood human speech, could be ridden without saddle or bridle (although they would tolerate such devices if needed), and lived to a great age — eighty years was not unusual.
The True Mearas had always been only a small number of animals, the direct descendants of Felaróf in the royal stables of Edoras.Other Rohirric Horses, the common breed of Rohan who descended from rhovanian wildhorses with pureblooded mearas crossed in, were sometimes known as lesser Mearas in contrast to the long-lived royal horses.