Stargate SG-1: Spirits

[McAvoy]

They never really figured out the Ancients backstory. They were in the Ori Galaxy at one point. They sent a ship millions of years ago in Universe. They spent a lot of time in the Milky Way to litter the galaxy with their experiments and technology. They were on Earth for who knows how long before Atlantis left the planet.

Seems like there are multiple versions of the Ancients. Maybe as a species they had multiple near extinction level events where they went back to zero and built themselves back up again.

Yeah it's just a mess.