The Ancients were a species of highly developed humanoids living on Mars.
After commanding Goomba to become guardian of the swamp, the Ancients slumbered until they were awoken by the human arrival on Mars. The Ancients hoped to learn about the human's starships so that they could head out into the universe. Over time the Ancients began abducting humans to learn their knowledge, the Martian Ghosts believed that the Anicents meant the humans harm and began ferrying them away from their Underworld. However, in turn the humans believed that the Martian Ghosts meant them harm.
Eventually, the Anicents learned that the Servo Toaster had the knowledge to revive all ten of the human starships. With the starships having been brought back to life the Ancients left to explore the universe and requested Toaster join them, to which the Servo agreed. (PROSE: The Heart of Mars)