Númenorean Horses
The Númenórean Horse was a very special breed, a descendant of the Horses of the Edain, who themselves had been a mixed breed of wild horses from Middle-earth and Elven-Horses from Valinor brought by the Noldor, and Horses from Tol Eressea, brought to Númenór as gifts by the Elves.
Few of these prized animals had been brought to Middle-earth during the days of Númenór, but some had survived in the Colonies of the Elendili, where they were interbred with indigenious races who were of a greater number and multiplied faster.
The Arnorian Greathorse, Arthadan Mid-Horse, and the greater Horses of Gondor were their descendants.