The Shattered Moon existed as a satellite, orbiting the planet known as Koboh; it was, in essence, a moon.
During the age of the High Republic Era, this celestial body suffered complete devastation due to an Emergence impacting its surface. This Emergence was just one in a series of Emergences resulting from the catastrophic collision between the massive freighter Legacy Run and a Nihil vessel within the confines of Hyperspace in 232 BBY. This calamitous event, which led to billions of deaths, later became known as the Great Hyperspace Disaster. The fragments of the Legacy Run hurtled through space at velocities capable of obliterating not only the surfaces of astronomical objects, but entire worlds; this is precisely what happened to the Shattered Moon, explaining its 'shattered' state.
Following this devastating collision, the Galactic Republic, working in conjunction with the Jedi High Council, issued an order to evacuate Koboh, its host-planet, to avert mass fatalities caused by fragments originating from the Shattered Moon. Shortly thereafter, a fragment of the moon collided with the planet, leading to the destruction of a portion of the Central Manse, which served as the primary operational base for the Jedi Order within the Koboh system.
By 9 BBY, the Shattered Moon's orbital path had achieved relative stability, with scattered rocky remnants forming a multi-layered ring encircling the remaining portion of the moon's equator, alongside several substantial fragments acting as independent, smaller moons. Local inhabitants of the Koboh system believed the moon to be haunted. It was on this moon that the Gen'Dai Rayvis met his demise, having been defeated in battle by Jedi Knight Cal Kestis.