Not much is known about the dead race of the Xaliurians but what is known is this is their last World-ship the ship seemed to be fully automated, but after the last of their tech was given to the Omniars and the ship last parked by a Black Hole where it orbits.
here is the final message of the Xaliurians:
"We are at our end. our species fell apart because the universe can no longer support us. We give you the Al of our technology, because you are the choice of ours, Accept our blessing, and you shall be the new caretakers for we will wither away. if you respect for us don't find what happened for us."