They had to have gone to the Ida galaxy also. Thats how the Asgard had a Stargate on their homeworld (when O'neill downloads the database the first time and gates to the Asgard homeworld in Ida)
A piece that is bothering me is the timeline of Ancient technology. The Destiny is supposed to be really old, it's got the oldest gate design, old systems, ugly design. Yet it's got the Kinos and a gate remote that shows nearby gate addresses and dials the gate. From what i gather the Destiny is around a million years old.
So how is it the million year old ship has older gate tech and such then the Atlantis city ship and all of the ships used in pegasus by the lanteans?
"The city itself is capable of space flight, and originally resided on the surface of Earth, on the continent that became Antarctica. Between five and 10 million years ago the Ancients left Earth with the great city, bringing it to a planet in the Pegasus Galaxy."
5-10 million years ago for Atlantis to move. But the Ancients had already seeded Milkyway with stargates prior to the move, so the MW stargates are all at least 5-10million years old. Which means, based on gate tech, the Destiny ship and it's seeders should all be considerably older.