From Dragon Eye Atlas
A "dungeon" is any kind of uninhabited (by intelligent species) mix of rooms and corridors that contains both dangers and treasures.
There are different kinds of dungeons in Auseka, from ancient ruins to abandoned dwarven cities. Many of these dungeons are known and most have been explored before - successfully or otherwise. In fact, exploration base camps or their remains can be found outside many dungeons and even at promising locations within the dungeon for the larger ones. Of course, where they failed, these camps are often abandoned, sometimes for years and decades, and have become a part of the dungeon. They might contain supplies as well as traps or other dangers of their own.
Other dungeons have been completely explored and their treasures plundered, only to be re-inhabited later and sometimes new treasures have found their way in, because a bandit group, a rogue mage or necromancer, an evil cult or some treasure-seeking monster have made the empty dungeon their new lair.