In my book series, the main antagonist is going to be a totalitarian culture descended from a long-lost human colonization effort in the Proxima Centauri system. They are completely isolated from the rest of the human race for the next 200 years after arrival and undergo a massive cultural and technological divergence. They then launch a successful invasion of the Sol system. My question is, what factors would be necessary for building an advanced civilization within 200 years? The planetoid on which the expedition lands is not naturally earth-like and requires the use of either dome structures or terra-forming in order to be rendered habitable. In terms of building a sufficient population, one of the advantages the colonists have is the fact that their ship carries a supply a human embryos (which are concealed from the authorities on Earth prior to departure). Another "advantage" I'm considering is the presence on the planet of a malevolent non-corporeal entity that guides the colony's development towards the form it has taken by the time of the Sol invasion. In the face of all this, however, the colony is cut off from any external source of supply or trade, existing in a state of de facto autarky. I'm a little worried that this requires a bit more suspension of disbelief than some readers will be willing to give, and I was hoping someone had some ideas on how to make this all seem at least logically sound if not completely plausible.