The Geography of Fantasy: Biomes and Civilizations

•Urdr Team

You don't need to be a geologist to build a fantasy world, but following a few basic rules of nature makes your map feel much more real.

1. The Water Rule

Rivers flow downhill. They merge; they rarely split (except at deltas). They always seek the ocean.

  • Mistake: A river running from ocean to ocean.
  • Fix: Rivers start in mountains/hills and end in the sea.

2. The Rain Shadow Effect

Mountains block clouds. This creates a wet side and a dry side.

  • Windward Side: Lush forests, rain, agriculture.
  • Leeward Side: Deserts, dry scrublands.

If you have a mountain range, put a jungle on one side and a desert on the other. It instantly looks realistic.

3. Civilizations Need Resources

Cities don't pop up randomly. They appear where people can survive.

  • Fresh Water: Rivers, lakes, oases.
  • Defense: Hills, islands, choke points.
  • Trade: River mouths, crossroads, natural harbors.

If you place a massive city in the middle of a featureless plain with no water, you need a magical explanation.

4. Biome Transitions

Biomes transition gradually. You don't go from a snowy tundra straight to a burning desert (unless magic is involved).

  • Sequence: Ice Cap -> Tundra -> Forest -> Grassland -> Desert -> Jungle.

5. Breaking the Rules with Magic

Once you know the rules, you can break them intentionally.

  • "Why is there a floating island pouring water into the desert?" -> Because a wizard did it.
  • "Why does this river flow uphill?" -> Gravity reversal anomaly.

The contrast between realistic geography and magical anomalies highlights the magic. If everything is weird, nothing is weird.

Conclusion

Start with physics. Add magic later. Your players will subconsciously appreciate the logic of your world, making the fantastical elements stand out even more.

Geography Continuity Traps (Quick Checklist)

As your world grows, geography contradictions show up as:

  • travel times that change between sessions/chapters
  • climates that flip without cause
  • cities placed where resources don’t support them

Fix it by storing a few hard constraints as canon:

  • biome + climate notes per location
  • standard travel times between hubs
  • resource notes (water, food, trade access)

Read next: Continuity Checklist for Novel Series

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