Sooner or later in gaming you start thinking about things a little too much and it’s about that sort of time that it hits you.
If this fantasy world is full of adventurers going about the place, adventuring, then why hasn’t this Dungeon/tomb/ancient temple been robbed already? Obviously it wouldn’t be much fun if it was cleared out and empty but if you want even the slightest amount of plausibility or verisimilitude then you need a better reason than that.
You can try some excuses, like ‘the ancient guardian that defends the place keeps people out’ but then adventurers tend to see that as a challenge, or ‘experience points’, rather than a reason to keep away. This is, needless to say, problematic.
Looking at the real world examples that we have – few as they are – we find that the spur that lead to the great archaeological, historical and treasure-type finds has been twofold. Imperialism and science. The quest to own and the quest to understand.
People like to think of their characters as heroes, but perhaps the closest we have to the role of adventurer in real history were the Conquistadors who rampaged across South America, the settlers of the American West or British colonialism in Africa, India and China. Wealth and power sought out to send back home and – later on – attempts to understand the past.
So, how might we replicate this in a fantasy setting?
Keep your old-world, high population, high civilisation, great feats of magic and technology that places it ahead of the rest of the world in terms of power, prestige, hunger and arrogance. Hold back some of the transport-magic and place some big natural barriers – like an ocean – in the way and then give your adventurers a whole new continent to explore, tame, loot, pillage and shape in their own way.
That gives you a huge amount more leeway to make shit up than the traditional lore-heavy set up, something more akin to the fantastical adventures in Edgar Rice Burrough’s books and also means you can build your world history as you go along, in response to character actions.