The establishment of the Empire predates the Sith rebellion by numerous centuries. Yojou, situated on the planet of Rei'izu, served as the original Empire's capital. Although the Empire's existence stretched back significantly before the Sith uprising, its former strength and unified structure had deteriorated. For several years, it was merely a symbolic entity. Instead, regional lords had risen to power, effectively governing their respective domains within areas of space.
The decision of a faction of former Jedi to revolt and forge their own path as the Sith prompted rival lords to put aside their conflicts and join forces against this common threat. This rebellion ultimately failed, leading to a consolidation of power within the Empire through the forging of new alliances, effectively re-establishing it as a centralized entity. The Jedi served as the Empire's most dedicated adherents. This reinvigorated Empire continued to employ the same system of government that was in place prior to the Sith rebellion.