Nobody knows exactly when dungeons first started to pop up but the 5th age is when they started to get more and more powerful. At a certain point like a dam breaking the monsters previously contained within started to spill out. Great swathes of land were taken over by the dungeon cores first fighting against the native inhabitants and then amongst themselves. The dungeon wars raged for 500 years until a faction headed up by the core now known as Dave rose up and instead of fighting started to protect the native human elves and other humanoid natives. The dungeons in question became bunkers with Dave and a group of adventurers forming the first version of the adventurers guild.

As the other cores refused to work together they were taken out one by one by the new guild. The next few ages saw the guild charter be formalized more. The guild leadership has 10 members. 4 adventurers 4 dungeon cores that are rotated regularly. The only two fixed members are Dave who has now become the dungeon core for the guild headquarters who only votes to break ties and Primus a non-voting member.

Primus was one of the adventurers that convinced Dave to switch sides, nobody, apart from Dave, of course, knows what race he was or what his original name is. The gods in reward for saving the world ascended him to godhood and made him in charge of the plane all of the guild housing is on. He stays out of guild politics but is known to have some favorites that he likes to pay attention to. And is known to play pranks on adventurers on occasion. The best-known one that gets repeated in taverns all across the world was the one time a high-level Orc adventurer picked up three girls that were fangirling all over him and when he entered his bedroom found the walls covered in pink with hearts and fluffy bunny toys spread out over the princess style bed. The rest of the story varies per telling of it.

After the calamity had passed dungeon cores agreed to follow new rules set out. Up to a certain threat level, they are allowed to do anything they want inside their dungeons. Once they reach a certain level of power they have to either follow more stringent rules, which have varied from age to age, or retire, willingly or unwillingly.

On very rare occasions Dungeon cores have asked to be elevated to city cores or fortress cores. In the first case, it's usually a core that has taken a liking to a certain area and its inhabitants. In the latter case, it's a Core that has taken a liking to a specific adventurer or cause. Sadly because they are often on the frontline of events that are age-ending they are often either destroyed although some of the more powerful ones are the reason civilization has actually survived this many calamities.

Finding, recovering, and restoring lost city and fortress cores is one of the standing quests the guild has. It's not easy as the core gems are often removed from their original positions. And certain calamities have drastically changed the landscape with continents being destroyed or sometimes even new continents appearing.