Coolmore Stud, which was set up in 1975, has emerged as the only true challenger to Godolphin.
John Magnier (son-in-law of the legendary trainer Vincent O'Brien) was one of the founders and remains the master of the operation.
Also involved are Michael Tabor and trainer Aidan O'Brien, whose phenomenal success has been fuelled by Coolmore's output of quality colts and fillies.
Coolmore's prize assets are usually retired after their three-year-old season but there are signs that this policy is being rethought with several stars - including Derby winner High Chaparral - staying in training as a four-year-old.
The jewel in Coolmore's glittering crown is Sadler's Wells, beyond question the best stallion of modern times, with over 50 Group One winners coming from his progeny.
Coolmore is usually associated with the dark blue Magnier colours worn by many of its stars, including Galileo, winner of both the English and Irish Derby in 2001.
But some run in Tabor's colours, like High Chaparral. Other partnerships include Mrs Sue Magnier and Sir Alex Ferguson, whose silks were carried by the record-breaking Rock Of Gibraltar.
Based in Ireland, the stud has stables all over the world, including the US and Australia.