Complex sentence: The Darley Arabian was one of three dominant foundation sires of modern Thoroughbred horse racing bloodstock, the other two being the Godolphin Arabian and the Byerly Turk.
Split into simpler sentences: The Darley Arabian was a dominant foundation sire of modern Thoroughbred horse racing bloodstock. The other two important foundation stallions are the Godolphin Arabian and the Byerly Turk.