A vague timeline at least, a more intricate examination of events would be better. This is an alien culture, a completely different people to Homo sapiens. In fact, the reason these people have stumbled onto a cluster of viable planets around a cluster of stars is because they were terraformed millenia prior, by humans themselves, who are now a vanished people. Not sure how viable it is, but it might be nice for artifacts or ruins from prior human settlement to come up in the background.
- Reliable interstellar travel is only 50-80 years old
- Several worlds colonized and in better political and resource shape than home (US history analogue)
- NO alien sentient beings to displace. Just flora and fauna. Terraforming?
- Terraforming - if you can make interstellar ships, you can terraform.