Basically they are the Forgotten Race. Which means nobody really remebers them, except maybe the Cetans and they are not likely to tell, are they. Not if it true that the Cetans were parasites that lived among the Forgotten Race and finally destroyed them.

There is a widespread belief that the Forgotten Race has been exploring and probably trading all around the galaxy before anyone can remember. This is thought to explain many very old artifacts that have been discovered on planets without any known contact. Some go as far as claiming that contact with the Forgotten Race could explain such universal habits as wearing funny hats at important ceremonies. This would be a folk memory of the strange space helmets worn by these visitors from far.

It may be that much of the advanced technology that the Cetans are trading on is just inferior copies of their technology. One of the strangest relics of the Forgotten Race is the Squatters’ Star, the original purpose of which is lost but the artificial environment remains habitable.