In 860-645 (USY), a great war took place between the ancient human civilization known as the Astral Federation as well as their numerous allies and the Shade Imperium. This war was waged across the universe and resulted in the death of trillions. However the Shade was clearly more advanced militarily and therefore had the upper hand throughout the majority of the war. This conflict lasted for nearly 10,000 years and is commonly called the "Great Universal War", the"Ten-Thousand Year War" or the "Pre-Unity War".
However the Shade who already had knowledge of the Triune race recognized that this was actually the 2nd Great Universal War. This conflict was shrouded in mystery and conspiracy and the exact details are not known. But in the end, Humanity achieved victory. With the Shade forced to retreat to the outer regions of the known universe.
After the retreat of the Shade, a council of inter-galactic leaders gathered together and formed an organization known as The Unity. Many of these leaders were human and that reflected in the rules, laws and decisions made during that gathering. This alliance of class four civilizations quickly grew in membership. Thousands more joined of all species and ideals.
The Unity itself is split into three separate councils. The Inter-Galactic Trade Union/ I.T.U which governs universal trade, the Council of Justice/C.O.J. which governs and enforces universal law and the Grand Unified Senate/G.U.S. which is composed of one representative per each member faction.
Overall these three sub-groups make up the most powerful class five civilization that currently exists. Similar to the United Nations, members of The Unity occasionally do battle it out but there are laws and restrictions of warfare put in place by the Council of Justice. However this has become exceedingly rare. The most common type of internal warfare in The Unity is economic and espionage.