Tartheans
The first known interstellar civilization, believed to have arisen around 1,200,000 BAF, named after the desolate planet Tarth where their earliest ruins were found.
Little is known about the Tartheans; the name is a modern designation, as their own name for themselves has not been deduced. Their remains are scarcer than one would expect of an interstellar civilization, suggesting they were fundamentally unlike modern societies or suffered some catastrophe. Their existence is heavily disputed in public, as their remains and technology are kept hidden by several powerful institutions studying them in secret.