As the only true ally of the Sith Empire, the independent systems of the isolationist Chiss Ascendancy occupy a unique position within Imperial power structures. Mandalorians serve the Empire for wealth and conquered factions submit out of fear, but the Ascendancy aligned itself with the Empire for mutual benefit. The exact details of this agreement remain a mystery to all but the highest-level Imperials and Chiss, but it effectively renders the Ascendancy a vassal state–self-governed, but a source of resources and manpower for the Empire as a whole. The Chiss Ascendancy’s internal governance mystifies most Imperials. The web of hierarchies and political influence networks that links the Chiss Ruling Houses is complex at best and impenetrable at worst, with political, family and military ties all playing a part in determining a person’s role in the Ascendancy. Internal power plays are common, but always occur within the accepted boundaries of Chiss society–even at their most vicious, the Chiss always maintain order.
In game codex (source)