For Galactic Historians, the Rise of the Shadow Empire marks the end of the period of the Successor States, after the close of events chronicled in the historical work, "The Fragmentation of the Imperium" by The Historian of Ossus.
The transistion moment during this period is the infiltration and seizure of New Tibannopolis by the Disciples of Ragnos ("DOR") and the New Trade Federation ("NTF"). This was followed by a period of expansion by the Sith Empire along the upeer Perlemian, and the 2nd Hutt Renaissance along the lower Corellian.
Failure of the RepublicEdit
Key to understanding this period would be a discussion of the failure of the Galactic Senate of the New Republic to contain the expansion of the Sith Empire. Several historical monographs record the political dissensions within the Republic, along with the rise of a Jedi philosophy of passivity and non-interference.