American Pharoah has carved out an historic legacy as the first Triple Crown winner in 37 years. Now the Hall of Famer is poised to join another exclusive club, if his exciting three-year-old Forbidden Kingdom goes on to win the Kentucky Derby (G1).
Here are Forbidden Kingdom’s pedigree fun facts:
1. American Pharoah would become the fourth Triple Crown champion to sire a Derby winner.
Gallant Fox, the 1930 Triple Crown hero, had his son Omaha succeed him by sweeping the Kentucky Derby, Preakness, and Belmont S. in 1935. Count Fleet, star of the 1943 Triple Crown, sired 1951 Derby victor Count Turf. Both Gallant Fox and Count Fleet appear as remote ancestors within American Pharoah’s pedigree. 
The most recent Triple Crown legend to achieve the feat is Seattle Slew, whose son Swale turned the Derby/Belmont double in 1984. American Pharoah has already emulated “Slew” at stud in one respect: both got off to a terrific start with their first crop of runners and ranked as champion freshman sire
While the 2019 headliner for “Pharoah” was Breeders’ Cup Juvenile Turf Sprint (G2) winner Four Wheel Drive, other foals of 2017 would gain in stature over time, including Grade 1 scorers Cafe Pharoah (on dirt in Japan), Harvey’s Lil Goil (on the U.S. turf), and As Time Goes By, who won the Beholder Mile (G1) the same day Forbidden Kingdom dominated the San Felipe (G2). 
2. American Pharoah descends from the male line of Derby winner Unbridled.
Unbridled (1990) is the latest of 12 Derby winners to sire a Derby winner, through his son Grindstone (1996). But his male line has flourished through other sons, including Empire Maker, whose dam, Grade 1 queen and Broodmare of the Year Toussaud, is by dual European classic champion El Gran Senor
Empire Maker, runner-up as the favorite in the 2003 Derby, rebounded in the Belmont. He went on to sire Hall of Famer Royal Delta as well as two Derby runners-up, Pioneerof the Nile (2009) and Bodemeister (2012). Both gained vicarious Derby glory through their sons; Bodemeister was responsible for Always Dreaming (2017), and Pioneerof the Nile famously sired American Pharoah. 
3. Pioneerof the Nile’s dam romped over Ajina at Churchill Downs
Pioneerof the Nile is out of Star of Goshen, a brilliantly fast filly who romped in her first three starts by a combined margin of 27 lengths. The last race of the sequence was the 1997 La Troienne S. at Churchill Downs, where she drew off by 11 lengths. The second-placer was future Grade 1 winner Pearl City, and the fourth was eventual champion Ajina. 
Star of Goshen’s sire, Lord at War, was a speedy chestnut who stayed the American classic distance of 1 1/4 miles. Champion miler in his native Argentina, Lord at War became a Southern California celebrity with major wins including the 1985 Santa Anita H. (G1).

4. American Pharoah’s dam was named Broodmare of the Year

Littleprincessemma was honored as Broodmare of the Year in 2015, in recognition of American Pharoah’s conquest of the Triple Crown and Breeders’ Cup Classic (G1). She has since produced two more Grade 1 performers. American Cleopatra, a full sister to Pharoah, placed second in the 2016 Del Mar Debutante (G1), and Chasing Yesterday (by Tapit) captured the 2018 Starlet (G1).

Littleprincessemma’s pedigree is all about speed. By the Storm Cat stallion Yankee Gentleman, she is out of Exclusive Rosette, winner of a five-furlong Florida restricted stakes. Exclusive Rosette’s sire is the obscure Ecliptical. A well-bred son of Exclusive Native (the same sire as Triple Crown champ Affirmed), Ecliptical didn’t live up to his pedigree on the racetrack.

5. American Pharoah’s family was cultivated by Fred Hooper.

Exclusive Rosette’s dam, Zetta Jet, was bred by a titan of the Florida Thoroughbred scene, Fred Hooper. Her pedigree sports three close-up crosses of Hooper’s speed machine Olympia

Both of Zetta Jet’s parents are Hooper homebreds. Sire Tri Jet landed the 1974 Whitney in track-record time that stood for three decades, and dam Queen Zetta is a daughter of Hooper star Crozier, runner-up in the 1961 Kentucky Derby and third in the Preakness. Queen Zetta is out of another all-Hooper homebred Miami Mood, a daughter of Greek Game and a mare by 1945 Derby hero Hoop, Jr. – famously one of the first horses he ever bought. 

6. Forbidden Kingdom’s dam scored her signature win at Churchill Downs.

Forbidden Kingdom was produced by Just Louise, who was 2-for-2 as a juvenile. Both wins came at Churchill Downs, in a five-furlong maiden and the six-furlong Debutante (G3).

Just Louise is by multiple graded-winning sprinter Five Star Day, a son of the Mr. Prospector stallion Carson City. American Pharoah is also a scion of the Mr. Prospector line, via the Fappiano branch. Thus Forbidden Kingdom represents a cross of “Mr. P” over Mr. P.

7. Just Louise’s half-sister once beat Rachel Alexandra
Just Louise is a half-sister to Sara Louise, who beat future Hall of Famer Rachel Alexandra in the 2008 Pocahontas (G3). But Rachel Alexandra turned the tables with a vengeance in the Golden Rod (G2), and their paths never crossed again. Sara Louise reverted to one turn for the remainder of her career, capturing the 2009 Victory Ride (G3) and Top Flight H. (G2). 
Just Louise and Sara Louise are out of the Grade 3-placed Kings Lynn, whose parents had rather different aptitudes. Her sire is high-class sprinter Mt. Livermore, winner of the 1985 Fall Highweight H. (G2) under 140 pounds, and her dam is 1993 Arlington Oaks (G3) heroine Til Forbid, runner-up in the 1 1/4-mile Alabama (G1) and such other prestigious routes as the Spinster (G1) and Kentucky Oaks (G1). Til Forbid inherited stamina from her sire, Temperence Hill, the 1980 Belmont S., Travers (G1), and Jockey Club Gold Cup (G1) hero during his championship campaign. 
8. Just Louise’s pedigree has a potentially significant pattern.
The most obvious duplication in Just Louise’s pedigree involves Blushing Groom, a French champion whose marquee wins came at up to a mile. An internationally significant sire (who factors three times in Derby contender Simplification), Blushing Groom appears here as the broodmare sire of Carson City and as the sire of Mt. Livermore.
Yet perhaps the genetic powder keg is hidden just beyond the fifth generation. For Just Louise also has two crosses of the successful broodmare Sister Shannon. She lurks in the back of Five Star Day, as the ancestress of champion Vanlandingham, his broodmare sire. Sister Shannon plays a more visible role as the dam of Temperence Hill.
9. The Rasmussen Factor is a recurring angle
Although Sister Shannon’s immediate pedigree isn’t fashionable, it nevertheless exhibits fascinating patterns of doubling-up on elite European ancestors. She has a common pattern of combining full brothers Pharos and Fairway (both major winners and leading British sires), thereby inbreeding to their parents, supersire Phalaris and blue hen Scapa Flow. But Sister Shannon also sports a duplication of the mare Serenissima, ancestress of the great Hyperion as well as Fair Copy. Thus Sister Shannon has the “Rasmussen Factor” of inbreeding to superior females, twice over, with Scapa Flow and Serenissima.
Just Louise has this same factor, being inbred to Sister Shannon. And Just Louise’s dam, Kings Lynn, also claims the Rasmussen Factor with her three crosses of *Papila. The Argentine mare is best known as the dam of Crimson Satan, the co-champion juvenile colt of 1961 who placed third in the 1962 Belmont and developed into a top handicap horse. Crimson Satan is an influence in Storm Cat’s maternal pedigree, but his appearance here comes courtesy of other descendants. 
Crimson Satan factors twice in Kings Lynn, as the broodmare sire of Mt. Livermore and the sire of Whitesburg (visible as the broodmare sire of Til Forbid). Kings Lynn is herself a direct matrilineal descendant of *Papila, who counts as her fifth dam (thereby the seventh dam of Forbidden Kingdom).
A representative of the number 26 family, *Papila is also the ancestress of Hall of Famer Tiznow and his relatives Oxbow and Paynter.