The 'thoroughbred 'horse racing we have today starts with just three stallions. Every thoroughbred racehorse today has one or more of them in its ancestry. Indeed, so much is this the case with one line that Eclipse, the great- great- grandson of one of them (the Darley Arabian, foaled 1700)is himself found in the male line of about 90% of all living thoroughbred racehorses.The other two were the Godolphin Arabian (foaled circa 1724) and the Byerly Turk ( circa 1680). All were imported to England to improve the quality of the native horses and were all, in fact, Arabians( though there was some confusion on nomenclature at the time).This was a controlled procedure; it was soon laid down that horses without the blood of one in their line were not eligible to race. The General Stud Book was started with an Introduction in 1791. It lists all mares and stallions used then and since. The Jockey Club had already been established in Newmarket to organize and regulate racing in 1752, by which time the Arab bloodlines were well established. Racing was not formally organized in its modern form in the US until after the Civil War, though racehorses had long been imported from Europe The American Jockey Club was founded in 1868.
