The only information on the Progenitors comes from the last flight recording of the Providence. The report talks of a "glowing ivory-white starship" that annihilated their engines within seconds of being detected. It was this engine failure that caused the Providence to be destroyed by an asteroid field.
"Progenitor" is merely a nickname used to refer to the origins or creators of ancient artifacts such as the Star Rails or the Lunar Gateway. It is speculated that Apsys explorers found a Progenitor artifact beneath the surface of Europa, but there is very little proof to back up this claim. The data recording from the Providence matches the description of other identified Progenitor artifacts in the galaxy, reinforcing the claim that remnants of this possibly lost civilization may still exist.
Dating of the Lunar Gateway reveals that these hypothetical Progenitors constructed it roughly four billion years ago, which would indicate this unknown faction was active before the first life existed on Earth. It is likely this faction was active within the galaxy before the Earth had fully cooled.
To date, very little information is available on the Progenitors. Unlike most Coalition science efforts, however, Progenitor information is available to the public. The reasoning behind this is unknown, but it is likely due to the efforts of Lunara Karta's interest in keeping the public informed.