Yadalla Prime was the location of a Romulan archaeological site suggested as a possible raiding target for a group of mercenaries working for Arctus Baran in 2370. (TNG: "Gambit, Part I"). Starfleet Command anticipated that Baran might attack this planet so a Federation starship was sent to this planet to intercept his ship. (TNG: "Gambit, Part II")
Yadalla Prime was called Yonada Prime in early drafts of the episode, a reference to the worldship in TOS: "For the World is Hollow and I Have Touched the Sky". The name was changed due to the need for Romulan origins for the planet. (Star Trek: The Next Generation Companion)
According to the Star Trek: Star Charts, on page 45, Yadalla Prime was located in the Yadalla system, in the Beta Quadrant. System primary was a Class F star. It had a magnitude of +3, which was 10 times brighter than Sol. In the ancient past, about 2,000 years ago, Yadalla was a destination on the Debrune trade route.