Those who came before...

It has long been a point of discussion between biologists, xenologists, and sociologists why exactly so many alien species with such similar biology have arisen in such close proximity at essentially the exact same time.  Some theorize that this is merely a cosmic coincidence, or evidence that life is so prevelant that at any given time there are always a myriad of technologically sophisticated species, others have a more directed theory.

These strange structures were discovered on Hapser IV
by a Linnerex survey team in the seventeenth century CE. 
There purpose has still not been determined but they
offer tantalizing clues about the precursors technology. 

It is established fact that there was another space-faring civilization that colonized a region roughly analogous to the modern extent of habitation.  The oldest known evidence of this alien society has been dated to between 250-270,000 terran years ago, and the most recent to less than 20,000 years ago.  This means that they were active star travelers for an incredibly long period from the perspective of modern species, yet evidence of their culture and society is sparse and difficult to fathom. 

It is known that they were so advanced technologically that it is not unheard of to occassionally find still-functioning examples of the art.  These functioning precursor artifacts are some of the most valuable items in existence and even the most mundane tool can fetch tens of millions of credits on the open market.  Many of these artifacts can be identified as highly-refined versions of recognizable tools.  Some however, have a purpose which is beyond contemporary science and they remain as curiosities in the possession of rich collectors, or as items of intense study at museums and research laboratories.

It is also believed, through limited translation of ancient data files, that the precursor civilization was destroyed by a cataclysmic civil war between two different factions.  One; called the Umbra by archeaelogists believed that in order to avoid stagnation, they needed to become one with their machine creations and enter into a new transcedant existance as hybrid virtual life.  They other faction, called the Mundi, felt that that would be a surrender of their identity to a soulless mechanical gestalt and thought that only through contemplation of material existence could enlightenment be achieved.

The fragments of these two philosophies have become the basis for several modern religions that have had some success with pan-sentient membership.  However, no matter how much is understood about those that came before, many mysteries remain as to where they came from, how they lived, and how they died.