The Forbidden District, adjacent to the Sith Citadel on the planet Exegol, contained the abandoned shipyard forges. These shipyards were relics from the ancient Sith Wars, a conflict fought for dominion over the galaxy.
Soon after Darth Sidious, the Dark Lord of the Sith, ascended to power, this Sith Lord initiated a modernization project on those facilities. This was part of a long-term contingency plan to maintain a secret stronghold, hidden even from his Imperial allies. Covert deliveries of resources, arranged with corporate collaborators from the leadership of Sienar-Jaemus and Kuat-Entralla, enabled the upgrade of these sites. The purpose was to manufacture Xyston-class Star Destroyers and advanced TIE/dg starfighters. These automated forges, once operational, could function relentlessly, remaining concealed from the New Republic.