gotta be honest, I copied and pasted this!! ...ultimately the thoroughbred lines known today can trace their male lines all the way back to three stallions from the 17th and 18th centuries: 
The Byerly Turk (1680-1696)Captured from the Turks in Hungary, he was brought to England by Colonel Robert Byerley. Due to a printer's error, the horse's name was registered in the General Stud Book without the final "e." 
The Godolphin Arabian (1724-1753)Given by the Bey of Tunis to the King of France, he was purchased by Edward Coke and subsequently presented to the Earl of Godolphin, at whose stud he sired the champion mare Aelima, imported to Maryland in 1750. 
The Darley Arabian (1700-1733)Thomas Darley sent this Arabian stallion from Syria to England. Ninety percent of all Thoroughbreds today are descended through his son Flying Childers and his great-great grandson Eclipse.