The Andromeda Galaxy, roughly 2.5 million light-years from Earth, is the closest spiral-type galaxy to the Milky Way.
While Andromeda had been observed and described by Humans in 964 and 1612 (respectively), it was only until approximately the 2200's that its inhabitants were encountered.
Later in the 2200's, the galaxy was visited by the Spung.
Somewhere in the Andromeda Galaxy is home to the Andromedans.
Andromedans take their name from the Andromeda Galaxy. Because Humans have had relatively brief interactions with the Andromedans, their English name is overgeneralized as from the entire galaxy. This is a clue that some time in the future there would be more accurate and complete descriptions of the specifics of Andromeda as well as its inhabitants.