From Halopedia, the Halo wiki
Partition is a human colony.
While this planet bordered on UEG trade routes, it remained undetected for centuries. Sometime during the Human-Covenant War, the UNSC Diadochi crash landed on this planet. The survivors lived amongst the ruins of the ship for years until rescue teams finally discovered them, in a thriving community. The planet was eventually named "Partition" in a nod to the Diadochi for which the ship was named.
Partition is the setting for the Halo 4 multiplayer map Exile. The now-cancelled Halo Online set the map Edge on the planet, with the map hosting a Forerunner databank amidst a verdant series of grasslands, canyons and waterfalls. Due to the game's cancellation, this appearance is non-canon.
List of appearances