Complex sentence: His wins included the 1995 Breeders' Cup Classic and the Dubai World Cup and the two-time American Horse of the Year retired the richest horse in the history of world Thoroughbred racing with earnings of US $9,999,815.
Split into simpler sentences: His wins included the 1995 Breeders' Cup Classic and the Dubai World Cup. The two-time American Horse of the Year retired the richest horse in the history of world Thoroughbred racing with earnings of US $9,999,815.