The Imperium is a large interstellar empire consisting of several civilizations but most notably the three that evolved originally on Algwethmai. The first three emperors, one from each civilization, established dynasties among their families. Each had their own ways of selecting successors to their thrones.
In general the emperors make rulings on matters of interstellar state and rarely interfere with the lives of their subjects and slave races, but in the event that whatever destroyed their two races happens to them the emperors can declare something akin to martial law and take control of their people and muster them to war.
Formed around the year 9550, the CIS was built out of the fear of whatever had happened to the Hakoduil and Ingla civilizations in the past. The CIS spread fast across their local area of space and soon had control of space 15,000 light years from Algwethmai. As it is a young government, there is little history save for what happened when the CIS made first contact with the Confederacy.
When the first broadcasts from Confederate starships were heard the CIS went on high alert. Their armies were mobilized but wisely the emperors did not attack as this was not what the ancient histories mentioned when the past civilizations fell. They invited the human ambassadors to their capital world where a loose treaty was signed. Since then CIS and the Confederacy have been on good terms.