Southern Edge is a new district for our favorite BG2 city - Athkatla - available from the very beginning of the game - it becomes available once you talk to Gaelan and hear his offer. The mod is to make the first hours of the game more interesting, as some player might have got bored with doing the same quests over and over again. The area isn't as big as Slums or as Bridge District, but it has its own main quest (introduced by a halfling named Mairo) and a series of mini-quests and encounters initiated by both some new characters, and some you might have met before.