The Core Alliance
As the expansion of humanity across the stars continued, the distances between them became greater and greater. Within a particular sector or system, it was still a short trip to another planet. Regions of space began to form under their own rules of law and government.
The core planets saw the problem, the writing on the wall so to speak and acted quickly to prevent the known universe from falling into a feudal system of conflict. Backed by the rich corporations who did business between regions, and a strong ship building industry, the core systems formed what would later become known as simply "The Alliance".
Their combined power was more than enough to put an end to any regional state government. As the influence of the alliance grew, so did it's abuses of power. Eventually, enough of the independent governments formed together to stop the alliance from having a complete grip on the known universe.