All I had to go off originally was the timeline created by Mike S and Brian J. I just wrote something to fit. It is the GMs who have made them such a huge force to be reckoned with… possibly going a bit too far in some regards. However, because there is no defined time between the “years” e.g. you could argue a stellar year is longer than an Earth year, the period they were active could have been quite long from a human perspective.
Time is always an abstract in our universe. I avoid relating it directly to Earth years. There are posts about time intervals and how they all fit together. Being a space faring, multi-species government, I am playing on the idea that we’ve moved away from time based on the cycle of the Earth.