Pegasus

Galaxy relatively near Earth's home galaxy, the Milky Way, to which the Ancients traveled when they left Earth with the city of Atlantis between five and 10 million years ago. There they also established a vast network of Stargates on over a thousand planets, which prospered for some time -- until the Ancients stumbled upon a world where the Wraith slept. This species awoke and ran rampant like a plague through the Pegasus Galaxy, feeding on the life-force of the human inhabitants seeded by the Ancients on many worlds until only Atlantis remained untouched. The city fell under siege for an extended period of time until the Ancients, defeated, decided to submerge it, the survivors returning to Earth to live out their lives in peace. The Wraith went into hibernation until a substantial population could be found that would allow all of them to thrive once more.

The threat of the Wraith has remained a dark cloud over the sparsely populated human worlds in Pegasus -- but the galaxy also offers great hope and potential to the eager explorers from Earth.