Or maybe long ago the People of Earth expanded out into space shortly after discovering phase space technology. Because of the great distances between these star systems. The original countries of Earth that controlled these colonies lost their control maybe 30-50 years after their initial settlements were established. Eventually Earth fell to a single government. And of course the notion that planets held many nations of many cultures fell to the wayside. At first these planets would have been independant with little contact other then trade between other planets for atleast the first 100 years. But eventually as populations grew and the needs for more resources became prevailant. The individual planets began wars between themselves and other planets of their system, only looking to further their own agenda through out the system they inhabitated. This would have caused countless wars. Some of which that lasted decades and even found themselves spanning a number of star systems as the fight for control expanded.
At some point, multiple star systems would come under control of an one government using their military might to enforce themselves. To keep these planets under their control they would be governed by individuals from the Home planet of the government that ruled that sector.
Within 1,000 years so many wars would be waged over unclaimed systems that it would be hard for anyone to count them. But at the end of this 1,000 years the multisystem factions would begin to use politics and trade as a way to influence their neighbors. As each faction would be strong and large enough to fend off any invasions. After years of mistrust and paranoia the different groups began creating alliances and treaties.
But it wouldnt be long before war was on the horizon. Near the edge of the cluster of factions came reports of a faction much larger then the factions alone. Ill call this super faction the Confederate Planets of Avidan. The factions homeworld was Avidan Prime. A planet that prides itself on war, these people pushed out looking to bring everyone into the fold. Their leader a dictator that passed down his place as ruler of Avidan Prime to his first born child. This would ensure that politics didnt get in the way of the vast empire the first dictator imagined for Avidan Prime.
The CPA was ruthless and wouldnt even waste time enslaving the people of any planets. These were the first people to use bombardment to annihialate entire populations. And the first to use colonists from planets already under their control to colonize newly conquered planets. For the first 4 years of the war only the planets sharing a border with the CPA threw their militaries at the CPA in a desperate attempt to push back the invaders. But this did nothing to stop the CPA from gaining control of these smaller factions. After a number of diplomats had been sent by each faction and had died at the hands of the CPA, they decided to send delegates to an emergency convention to discuss a unified front against the Confederates. After the terms were hashed out the individual planets sent the majority of their Military forces to serve under the newly formed United Planets Defense Force. A strictly military organization that had a strict code of laws that only allowed them to use their forces against the CPA.
The CPA for the first time now faced a force equal to their own. The war would last 100 years, with entire star systems changing hands multiple times. Some star systems were abandoned entirely by both sides after planetoids were sucked dry of any resources needed for the conflict. Individual planets populations up and left disappearing into the vastness of space never to be heard from again.
Eventually the CPA fell under its own pressure unable to continue funding the war as well keep their planets from rebelling. This came to be known as the 1st Great Phase War. or GPW1
With the fall of the CPA the UPDF should have shut down all operations and the individual factions fleets should have returned home. But after 100 years of fighting the UPDF had become its own faction. Holding a number of systems, a size that rivaled even the largest of the remaining factions.
Again war came to the factions when the UPDF didnt relinquish their control over the fleets that were now manned by UPDF loyal troops. But by this time the factions had built up large enough defensive fleets to hold off the UPDF. This would become the 2nd Great Phase War. It would last another 10 years. Finally ending when the different factions focused their operations on the UPDF and overwhelming them from all sides.
With the fall of both the CPA and UPDF the factions went back to realitive peace. And decided that they would only deal with outside factions on the means of trade.
After 150 years of peace a faction known as the Terra Corporation, A multi star system controlled by a corporation instead of a political government began sending envoys to other systems in the hopes of uniting the factions into a peaceful empire that would lay down their weapons and begin trading with each other.
This would be the start of the Trade Order. Which wouldnt come about for another 100 years.