ORIGINS OF THE BLOODED HORSE
The Thoroughbred was developed in England between about 1680 and 1750, when some 150 stallions were imported from the Middle East. Today all Thoroughbreds trace their ancestry back to three of these stallions - the Byerley Turk, the Godolphin Arabian, and the Darley Arabian. The imported stallions were sometimes mated with mares imported from the Middle East, but for the most part were bred to native stock. These native mares were mixed lineage and generally failed to breed true. The imported stock helped to overcome this and to stabilizing the breed.
The early development of the breed was hampered by lack of accurate breeding records. Often, several sires might have the same name, and it was not uncommon for a horse's name to be changed when sold. This would not be totally rectified until James Weatherby produced the first General Stud Book in 1791.