Polis Massa was an asteroid field located in the Subterrel sector of the Outer Rim Territories, far from any major hyperspace lanes. At some point, Polis Massa was a planet located within the system of the same name, though it was destroyed by a mysterious cataclysm. The Archaeological Research Council of Kallidah established a base on one asteroid in order to excavate its surface to study the reasons behind the planet's destruction. The Kallidahin eventually came to be known as Polis Massans.
Following the execution of Order 66, Polis Massa became a safe haven for surviving Jedi. Shortly after the lightsaber duel between Obi-Wan Kenobi and Darth Vader on Mustafar, Padmé Amidala gave birth to twins, Luke and Leia, at the medical facility located on Polis Massa.