Cetan civilization

The original human term for the renlai, since, before the Purge, an extensive amount of colonization was shown to have existed in Tau Ceti, including the development of stargates. Radioisotope dating suggested an age approaching seven billion years - nearly half as old as the Universe and at the time considered to be aeons before life could have feasibly evolved.

Similar relics - clearly belonging to the same civilization, were discovered in Gliese 783 and 82 Eridani. Given the age of the civilization in question, this implied that they were not merely a regional but a galaxy-spanning empire, if not further. Because of this, some took to calling them 'precursors' or 'ancients' and other such terms.

It was known - even before the Purge, that they had undergone some sort of conflict. The full extent of this war - and their revelation as the renlai - was not discovered until well into the Diaspora.