While an elaborate history isn’t needed, a sense of the past can add realism to our work. How much history we’ll need depends on how much we’d like it to inform the present. A short story needs little, but an epic trilogy of adventurers traveling across many lands requires it. The sovereign powers they traverse have history with each other, and some of that will be recent, such as a war or a new ruler who is crushing freedoms for the people or reducing restrictions. Even if we don’t want to comment on this sort of thing much, characters will be aware of these new ramifications of entering another land. Traveling through similar places results in a flat narrative.
Science fiction often focuses on the future, given the presence of technologies that don’t yet exist, but that future is far enough away that there’s still past that’s ahead of our current timeframe. In other words, a story set on Earth in 2500 AD has 500 years of history that hasn’t happened yet. In settings not connected to Earth, we can create future history without worrying about how we get there.
A common fantasy trope is that ancient, and long-vanished, civilizations have left relics that characters discover and use. These can include magic items, forgotten spell books, powerful creatures, and ancient, long overgrown cities that harbor horrors that will one day reawaken. The characters responsible for the demise of these civilizations can become legendary figures, which is covered in “Creating World Figures” from Creating Places (The Art of World Building, #1). We should have a high-level idea of what culture created these items and how that culture disappeared, but details included in the narrative can be sketchy because in a world with limited technology, the average person knows less history. This is true even in an advanced society such as our own, where most people aren’t worried too much about the past; that said, we pick up little details from the news and entertainment, so we have a general sense of events without depth of knowledge.
The architecture of ancient civilizations can provide a sense of being alien and therefore unsettling, allowing us to characterize a scene with description and our characters’ reaction to a location. To do this, we should decide what form of government this decrepit place had. There’s a tendency toward the brutish, hulking, and threatening styles associated with authoritarian regimes (and the foreboding they produce), but we can also have an elegant place designed by an enlightened species, whose city has been destroyed by war or plague (resulting in a sense of nostalgic loss for visitors). Deciding on the reaction we want can help inform our decision.
Post-apocalypse works need a cataclysm that has created the present scenario. The cause can be technological, biological, supernatural, or somewhat ordinary (such as an asteroid strike). A world with gods might want a moral reason for the destruction, such as gods abandoning a wicked species. In Dragonlance, human pride caused the gods to stop answering prayers for hundreds of years. Such a scenario allows commentary on humanity’s failings.
We might have multiple continents and therefore a whole world for which we’re creating history. In this case, we might want to organize the history we create into smaller sections, possibly in different documents. World events, such as gods inventing a worldwide species, or a plague that spreads between continents, would go into one file. But we otherwise might want to organize our events by a continent or region.