Lord Zack's Space Opera
Pegasus is a dwarf galaxy in the local group, approximately 3 million light years from the Milky Way. The Ancients created a large empire there before being driven back by the Wraith. It is home to populations of humans. The Atlantis Expedition began exploring it in the early 21st century, a mission continued by Starfleet.
While Starfleet has a handful of intergalactic hyperdrives, most exploration is based around the Ancient City-ship Atlantis. There are also a few starships based out of the Pegasus galaxy and a few starbases.