Magrex (orignally Mining Storage-Processing Center 4K-35) was a moon in the Colonies region of the Galaxy. It was settled by the Republic around 2,500 BBY, but was always meant for factories and processing centers, not colonies. Over the years, in was transformed into a huge industrial ecumenopolis, similar to Loria, with artificial gravity and atmosphere making it more inhabitable. The identification code of MS-PC4K-35 was shortened and modified to Magrex by local workers, and eventually became used on official maps and charts.
The small world soon developed a mechanical gray appearance, which was not only because of the plain-colored factories, but because clouds were controlled to stay together until they were forced over a filter-reservoir.
Admiral Erk Grekins used the moon to build his army and starfleet. He used the base's main reactor to power up or build many factories, and defended his ultimate construction ecumenopolis with thousands of gun turrets, shield generators, and ground forces. Several advanced space stations and an assigned fleet protected the moon from orbit.
Dispite the defenses, Grekins did not wish for it to be discovered. However, after the Clantosh Campaign, several enemy Remnant warlords discovered the location at around the same time the New Republic did.
In the following battle, which had over four battling factions, warlord Grekins's factories were all either captured or destroyed. It is unknown what the New Republic did with the moon afterward.
Later, the New Republic made vehicles factories on the planet. Bounty hunters, Imperials, and Separatist holdouts attacked the world. It was soon part of the Empire.