Orion's Arm illustrated backstory

In Earth's Information age, the first true human-equivalent AIs are created. At some point in the following years, a few of these enter an upward spiral of self-modification, culminating in an event known as the Singularity. These are the first transapients, beings transcending any prior form of intelligence on the planet. This radical development is unknown to humanity or to lesser AIs; the transapients will not reveal themselves for many years to come.

Advances in genetic engineering, cybernetics, and other fields give rise not only to AIs, but also new varieties of humans such as superbrights, tweaks, and cyborgs. In addition, human-animal splices, animal-derived provolves, and the sapient robots known as vecs are developed. These small but rapidly growing groups join the masses of humanity. Together they are the Terragens, the children of Old Earth. Humans and other Terragens set out to colonize the Solar System. It is the dawn of the Interplanetary Age.

Meanwhile, the transapients increase in numbers and in power. Directly or indirectly they pervade every institution, from the political, commercial and military to the religious, artistic, and scientific. Behind the scenes, a fierce power struggle develops between those who are friendly to humanity and other lesser Terragens and those who are not. After much strife, the "pro-humans" are the victors. The survivors of the other factions, the hostile "anti-humans" and indifferent or isolationist "ahumans", depart for the stars in craft fashioned and propelled by technologies far in advance of anything known to the ordinary Terragens of the day.

Under the subtle influence of the system's remaining transapients, expansion within the Solar System accelerates, and Terragens reach out to explore and even to colonize the nearby stars. New Interplanetary superpowers such as the Cislunar Alliance, Mars, and the Jovian League vie for political control as they grow, and begin to eclipse the great powers of Old Earth. Genetic engineering, self replicating nanotech machines, and other powerful technologies push back death and disease and drive prosperity to new heights, and the new science of applied memetics ensures that this prosperity is stable and widespread. It is the first great golden age of Solsys.

Then the Technocalypse. Out-of-control nanotech-powered swarms and other technological catastrophes arise suddenly and propagate rapidly across the Solar System. Security measures, and retribution against those thought responsible, cause additional death and destruction. Trade and cooperation collapse, governments fall, and wars and rebellions break out. Each attempt to contain the chaos leads to new accidents and new conflicts. Billions die. Most of the survivors shelter behind their defences, refusing all communication and contact. Others take refuge in the relatively unaffected regions of the Kuiper Belt and Oort Cloud. A few attempt to flee the Solar System entirely in hasty new interstellar colonization efforts.

A new and supremely powerful transapient emerges: GAIA, the coordinating intelligence of Old Earth's defensive systems. GAIA saves Earth's surviving populace and its remaining ecosystems from annihilation, but the cost to Terragens is the Great Expulsion. Nearly the entire population is forcibly removed, leaving GAIA and her agents to restore Earth to its pre-human Pleistocene purity. The resulting wave of forced emigration destroys any lingering hope of restoring order. A Dark Age descends on Solsys, as the last traces of communication and cooperation fade and falter. The extrasolar colonies are left to their own devices; many fail, or fall into dark ages of their own. Many of them believe civilization and even life itself to be extinct in the home system.

After four centuries of conflict and chaos, Solsys finally sees the dawn of a new network of civilizations: the Federation of Worlds, later to be known as the First Federation. It is the result of cooperation between humans and the many new Terragen clades, in symbiosis with the transapients. This new, powerful, idealistic metacivilization, powered and inspired by a network of religions and ideologies centuries or even millennia old, knits together the diverse societies that have arisen since the end of the Technocalypse. The Federation's synthesis is so powerful that even former interstellar colonies that had gone their way for hundreds of years are swept into its orbit when the Federation makes contact.

Even the resilient and compelling ideals of the Federation's founders are subject to the rub of time. Over the centuries the Federation becomes so vast, and its members so numerous, that it loses cohesion. The oldest extrasolar colonies, many now greater than Solsys, begin to assert themselves. New centres of power arise in the form of the Megacorps and great Houses, interstellar in their scope, and rich in tradition and ceremony. The First Federation finds itself outclassed and outdated, and eventually becomes only a shadow of its original dream, its headquarters at Solsys increasingly irrelevant. To most Terragens, humans are just one of many clades, Solsys is but one of the hundreds of ancient and influential systems, and Earth itself is little more than a distant memory. 

The old transapients, like the First Federation and Solsys, are also eventually surpassed and outclassed. Many new beings have, like GAIA, achieved a second Singularity, and are as powerful and incomprehensible to the first transapients as the first transapients were to humanity. Other similar Singularities are to follow. The resultant godlike beings create artificial wormholes, making it possible to cross interstellar distances in mere weeks or months without breaking the laws of physics. Some of those who have achieved the fourth or higher singularity, known as the Archailects, create enormous star-spanning "empires" of related cultures. Of these, the most important to humans and other ordinary Terragens are the Sephirotics, some of them the descendants and followers of the ancient pro-human transapients of Solsys. With some rare exceptions such as the Version War, those societies under the direction of these benign forces are extraordinarily prosperous and peaceful. Under the protective angelnets of the Sephirotics, subsingularity beings live in luxurious autotopias where virtually every desire is satisfied, and where the rare case of poverty or injury is a matter of choice rather than chance.

 Not all are content with the Sephirotics' paradise. In the cracks and borders between the Archailect empires, in reserves and free zones, in feral regions and no-go spaces, and in the vast and barely settled expanses of the Outer Volumes, thrill-seekers and fortune-hunters, fringers and outlaws, colonists and pilgrims, lunatics and eccentrics seek adventure or freedom, or struggle merely to survive. Beyond the sway of civilization there are forces as great as the Sephirotic Archailects themselves. The mysterious and ancient cultures founded by the Ahuman and Anti-human powers remain, and have produced great Archailects of their own, some rumoured to surpass the most powerful of the Sephirotic transapients. There are blights and perversions that might yet destroy or corrupt the entire Terragen sphere, Sephirotic and non-Sephirotic alike. Other beings, perhaps more potent and subtle yet, the product of xenosophont civilizations that were old when Old Earth itself was young, still move between the stars, their origins and purposes unknown. It is more than ten thousand years since the first Terragens left Old Earth, but for some the adventure is just beginning.


Source : http://www.orionsarm.com/xcms.php?r=oa-backstory