Rock Gnomes are the most common type of gnome among the known world, and indeed, when one speaks of a "gnome," chances are he or she means a Rock Gnome. While not a populous race in comparison to humans or other demi-humans, they are encountered in a wide variety of environments, showing no particular preference for any one type of climate. They do, however, tend to make their homes in areas with an abundance of natural rock (even if it's invisible under a layer of loam and forest).
Gnomes travel frequently among their communities, and many of them will venture into human or demi-human cities out of curiosity. They mix well with halflings and find life in a halfling village quite pleasant. Unlike halflings, they have no particular compulsion that holds them to their own homes or locales, and their long lifespans afford them the time to indulge their curiosity about how other races live.