Fly Guy shirt
Only a few thousand years by most estimates. Ancient chinese astronomers did not have it on their star charts. And they were pretty detailed. Even by our standards. If you look at Fly Guy shirt thru a large telescope you can still see the hot blue gasses coallessing into what will be more stars at some point. An alien society could not possibly evolve in the few thousand years the Pleiades has been around. Nor could planets form in such a short time to sustain life.
Fly Guy tshirt, hoodie, youth tee and ladies tee
One thing is they take and use dark matter the same way people use to use gods to explain things without explaining them. Other than that Fly Guy tshirt itself is either a very old galaxy and the stars have faded out or super nova-ed leaving a bunch of smaller black holes. Or it is a normal or collided galaxy that gathered a massive amount of super giant stars that have very short lives and they supernova within billion years of their creation.