An Italian trainer Federico Tesio once summed it up :-
“The thoroughbred exists because of a piece of wood: the winning post of the Epsom Derby”
Derby and Oaks are one of the five classics. One Thousand Guineas and Two Thousand Guineas for the mile and St Leger for a mile and six furlongs. St. Leger is the oldest race but nowadays horses tend to go for the Arc de Triomph. Hence no great Triple Crown winners in recent decades.