The Ruji were a species who had made contact with the United Federation of Planets by the 24th century.
When Benjamin Sisko was in his late 20s, he and Curzon Dax attended the running of the Rujian Steeplechase where they met "these gorgeous seven foot Ruji twin sisters" that Curzon knew, and together they proceeded to get into some mischief.
Sisko recalled the story several years later with Julian Bashir while the two discussed the new Dax host, Jadzia. (DS9: "A Man Alone")