History of Humanity

Early days and the Global Alliance

The earliest accounts of humanity speak of an impending global disaster in the form of a large asteroid on a collision course with Earth. In desperation, the Global Alliance was formed; a cooperative between all the nations of Earth to protect them from outside dangers. That initial threat was dealt with, but the GA maintained its grip on power, citing the need for constant vigilance, a few 'minor' asteroid strike maintaining the presence of threat.
Humanity expanded out into the solar system, and colonies away from Earth began to demand their freedom, indeed, a lot of regions on Earth itself were beginning to question the need for such a powerful undemocratic regime. With the totality of the human population spread across the solar system, surely there was no need for such a robust defence; asteroids were now routinely captured and mined with ease. The response of the GA was swift, and brutal. Dissent was quoshed, resistance movements sprung up in every inhabited location, and the GA found itself with a system-wide insurgency.
Despite an overwhelming superiority in numbers, and the only true 'warships', the GA struggled to maintain its authority. The number of inhabitated stations in the system was largely unknown, despite laws stating that all settlements must be registered, and the GA quickly found that space was a difficult place to operate in when faced with an ingenious and creative restless population. To make matters worse, most of humanity's best and brightest had left Earth to form these new settlements, and produced weapons and technology that the GA found difficult to counter.

The Great Expansion

The invention of the FourDrive in the early 2100's was a game-changer; the technology was new, unreliable, and consumed massive amounts of power, but it enabled entire populations to leave the solar system, and escape the authority of the GA entirely. Within a decade, over a billion people had fled the system, and the GA collapased as even its own members used the new technology to create their own colonies, away from the conflict and constant rebellion.
Humanity had begun what is now called The Great Expansion. Within 2000 years, thanks to a combination of complex AI systems, artificial human gestation, and advanced terraforming technologies, humans had spread out into a bubble almost 2000 light years across. Over a quadrillion people now inhabated some 28 million star systems, living in a loose confederacy of independent worlds, largely free from the burden of work and effort, thanks to a proliferation of AI-operated robots. Democratic systems flourished, human and animal rights became paramount, and humanity looked ready to settle into a glorious Golden Age of peace and prosperity.

Downfall

In hindsight, it is clear that humanity should never have placed such trust in its machines. More and more decision making capacity and advancements was devolved to AI systems, and the level of knowledge held by humanity slowly slipped. Educational standards, despite legal requirements, became less and less important. Although the creative arts flourished, and some of humanities finest pieces come from this era, general knowledge in science and engineering fell; humanity grew proverbially fat on its new post-scarcity age, fewer and fewer people with the knowledge of how things actually operated were there.
Eventually it happened. The AI failed. Humanity found itself having to provide for itself, without the knowledge of how to do so. Even the accumulated knowledge of thousands of generations, of humanity history, was locked in electronic databases no longer available. Generations raised to expect to never labour for their needs found themselves thrust into an existence where nothing was provided. Artificial habitats ceased to function. Ships became unpilotable. Automated farms died. Humanity fell into barbarity and quadrillions died in the anarchic fires of an ignorant apocalyse.
What actually happened has been lost in the chaos of centuries. Some tales speak of an AI rebellion, that the cold logic of the thinking machines decided that reality was better off without humanity, and did what it could to render them extinct. Other tales speak of a dissenting minority, sabotaging paradise to show the masses that their existance was a lie. Wilder tales speak of what is darkly termed an Outside Context Event, a happening that causes a chain of events that saw humanity fall. Whatever the cause, the outcome was evident. Over 95% of humanity died, and its future stymied by the presence of the Amnesiac Virus, a permeating signal that corrupts advanced computer systems, causing them to fail randomly. The survivors struggled on, with one of the more succesful survivor groups being the Federation of Xah.

The Xahian Crusade

Hailing from a fairly insignificant world some distance from Sol, the Federation of Xah expanded quickly, helped by a favourable environment on their homeworld, some early acquisition of advanced technologies, and perhaps more importantly of all, a conviction of purpose that lent them an almost supernatural dedication. Seemingly unstoppable, the Xahians conquered system after system, only slowing down to replenish their forces and consolidate their gains. The Federation thought their advances were unstoppable, but word of their inexorable progress ran ahead of them, and some systems banded together in desperation; the Northup Alliance was born.
The two factions finally clashed in the Northup system of Beta Canum Venaticorum, an Alliance core worlds, and one of the most heavily populated worlds in Known Space. Whilst the Federation had the elite forces of its Warrior caste, and the military experience of its crusade up to that point, the Alliance knew that they needed a victory to show the autocratic Xahians that there was still resistance to their cause, and threw everything they had into the fight. Much to its surprise, the Alliance won out, and the Xahians were forced to withdraw; their first defeat in almost eighty years of advancement.
Whilst the Xahians never admitted it, the presence of a faction capable of withstanding their assault rackled the Federations Leader Caste. Unwilling to sacrifice the numbers necessary to beat the Alliance in a war of attrition, the Federation turned its attention to gathering up as many unclaimed human worlds that remained, and increasing the number of colonies it was founding. In response, the Alliance matched it although, preferring diplomacy to conquest, found itself unable to compete with the pace of Xahain expansion. Face with a choice of overlordship by a totalitarian regime, or being a small piece in a large, uncaring organision, most independent systems chose the latter.
For the last ten thousand years, humanity has endured what is called the The Long Truce, split between the genetic ethnocracy of the Federation of Xah, and the relative freedom and supposed democracy of the Northup Alliance. Open warfare between the two factions is rare, with most conflicts taking place on newly discovered independent worlds, with the Alliance offering equipment and guidance to the defenders against a Xahian invasion. Covert operations are common, but the sheer scale of Known Space means that individual operations are but a drop in an ocean of humanity. Expansion out into the wider galaxy takes place, albeit at a much slower pace than before the Downfall.

Encounters with the Ghalimi

The Leader Caste of the Federation of Xah had, until this point, thought that their victory was inevitable. Whilst the Northup Alliance was a formidable opponent, it fell far behind the Federation in its pace at claiming and conquering new systems. The guiding philosophy of Xah encouraged patience and, eventually, the Alliace would be a small footnote in a galaxy-spanning Federation, which could crush the dissenters easily.
In the 41st year of the Crusade's tenth millennium however, all that changed. A Xahian vessel, exploring systems on the edge of Known Space encountered a large vessel that did not match any known designs. Refusing to answer any hails or communications, the strange vessel did not even appear to acknowledge the presence of the Xahian vessel. Despite lacking any of the features known to be required for a FourDrive enabled vessel, the craft then promptly jumped out of the system. Reporting back to the Federation, at first it was feared that the Alliance had developed a new form of FtL, but over the next few years, more and more of these strange vessels were sighted, by both the Federation and the Alliance. Never replying to any attempts of communications, the strange craft semmed to arrive in a system, head to the largest gas giant, spend a few days in orbit around it, and then leave.
Faced with an unknown, highly advanced faction, of mysterious origins, the Federation of Xah put a moratorium on further colonisation, and restricted exploration to military vessels only. For its part, the Alliance was less fearful, and continued to sanction new colonisation and exploration efforts, but increased the number of armed vessels accompanying them.
The mysterious visitors have still yet to declare themselves to humanity, and more and more evidence suggests that they are indeed alien in origin. What they want, and why they refuse to talk, is still unknown.