Under the Dungeon Types Section of the site I touched on the back story of a dungeon as a way of determining the dungeon content. This section focuses more on the back story as a whole, even the parts that the PCs don't end up knowing. The backstory discussion under dungeon types was more about plot, this section impacts more on scenery. Here the back story matters nor for which entries from the Monster Manual or sample traps list from the DMG you choose, but for the general flavor and feel. Most important of all, if you play your cards right, i.e. if you set the scenery details up right, you will have suspended your player's disbelief. That is the main goal of every DM. That's what makes DMing fun. Monte Cook and a number of other people have said that being a good DM is like being a good writer. They are very, very right.

So: Scenery-based backstorying. Setting up the scenery and detail. To begin, make sure that you have the back story reasonably flushed out and prepared. This does not mean that you write a short story fit for Amazing magazine, or even that you write a historiagraphy of Melkor's Caves. That much detail is unnecessary. Back stories exist to make the situation or character more real. They do not exist to drill your Player's with social studies papers. The PCs will probably not get the entire back story. They don't need to (unless you are running a mystery-based campaign, where discovering the back story is the key to winning.) The back story exists so that what clues they do discover fit into a general pattern.

To explain by example: You're starting with a new party of players. Maybe the players are veterans, maybe they're newbies, but they are all making first level PCs. You as the DM are flipping through the challenge rating list. Ah-hah! Kobolds! Perfect first level fodder! Or maybe not. Do you really want to sit and work through a whole lair full of traps and ambushes? (Take a look at Monte Cook's article in the June 2004 issue of Dragon on 5 room dungeons while you are pondering this.)

At this point you can a) work like a dog on a really clever kobold lair, and those pizza-eating, doritoes-snarfing, soda-guzzling ingrates had better appreciate it, b) buy a Slayer's Guide to Kobolds and just run the lair in the back of the book, c) do a "kobold download dungeon" googling, and get wotc's kobolds as elite opponents along with some blog authored by a gamer who is whining about his life (or even more pointlessly, this web page), d) throw your hands up in the air and realize that goblins are sloppy, disorganized creatures, so you'll just toss a few into a small cavern system, because the lawful, organized kobolds are too much work, or e) make a quick back story as to why a handful of kobolds would be encountered by your PCs in an area that they've only recently moved into so that the traps are few in number, i.e. manageable to 4 1st-level newbs.

Yes I know that the above paragraph is an obscenely long run-on sentence. Stay with me please. (Blasted ADD-infected generation Y!)

I was sitting in contracts class last winter, ruminating about subcontractors and the Supreme Court of Ohio, when a thought hit me. What if an unscrupulous human contractor hired kobolds to do the sewer work contract that he won from the city? (Yes, I live in Chicago, subcontractors relying on LE creatures is part of life here. No, I do not think about DnD during every boring point in law school. Sometimes I'm surfing the net reading webcomics. Scott Kurtz rules.)

Anyway, it made sense. Nuetral human, self-interested, low bids the contract for the village to install the sewer piping, finds that he can't do it for the price that he said he could, and gets desperate. So the contractor thinks, who's good at digging and mining, works cheap, can do organized work and unlike CE orcs might keep their bargain? And they're small-sizaed creatures to boot! Somehow he makles contact with a kobold band, smuggles them into the city, and puts them to work. (Maybe they work for pickled eggs, or I am still thinking about what a great movie HELLBOY was?)

Note that I skipped over how this human made contact with the kobolds and how he smuggled them in. That's a hook for a later adventure, when the PCs are tougher, and feel like taking on the Smuggler's Guild.

Now, said human contractor can't fire all of his workers, that would be too obvious. He lets half go, and replaces those with the kobolds. The kobolds eat less, work in the dark (saving money on lantern oil), and are better at it. So, you have a kobold nest under a city (or large town), and a desperate N human who wants it to be hidden.

Where do the PCs come in? Any number of ways. Maybe one of the kobolds broke through a wine cellar and had a party. (Watch Poster "Wanted, Kobold alchoholic.") Maybe somebody spotted a kobold, who knows? That's a separate issue called a plot hook. The point here is that you have a back story. Now, when the PCs attack the kobolds, the find maps of planned tunnel routes, mining equipment, and notes written on the wall in chalk about bore diameters. Perhaps they make a listen check and find two kobold mining chiefs arguing about which angle to dig the new tunnel, while the kobold warriors/slash miners sit around and roll dice or joke. A PC that speaks draconic would be very interested in the conversation. Without actually thinking about it, it makes sense that there are not traps and ambush points every other five-foot square. The kobolds are building, not defending. Of course there is a series of rooms that they carved out for their own purposes, and you can bet that there are certain hidden tripwires. It's hard to spot a tripwire obscured by two inches of water.

I went ahead and used the scenario that I just described. The players really got into it, and their disbelief was totally suspended. When they got to the final part of the dungeon, a makeshift kobold temple with a second-level kobold cleric who had domains in Law and Luck, my room description contained the following sentence. "Interestingly, on the wall above the altar, is a piece of parchment. It is within a wrought iron frame, and written in both common and draconic." One of the PCs made the spot check, and saw a human name - the contractor who hired the kobolds.

Tactically the room was very tought for the PCs. The five kobold worshippers who were with the cleric ducked behind the pews for half-cover, and the pews had been set up so as to catch intruders in an enfilade of crossbow bolts. But the point is that the PCs believed it. They got into the battle, and totally went for the situation. To them, realizing that the kobolds had been hired to dig tunnels by a shifty contractor made sense, given what they had encoutnered so far. (And yes, I did some foreshadowing with random rumors about trouble with public projects, etc.)

In summary, the back story gives you a place for clues, and a groove for the players to get into.