A town in the tropical rainforest, on a river

With what grows here (yams and other tubers, rice), this land can feed a town of about 7,900 people from farms less than a day's cart from its walls, about the size of Winchester around 1300.

Build a town in the tropical rainforest, on a river

A town of 10,000 here

Its grain comes from 28 km around, 1.5 days by cart (strained). About 690 villages and 79,000 country people farm it, and the town keeps about 40 scholars. Grown to 40,000 people, its grain comes from 56 km around, 2.5 days by cart (fragile). On the water, ships can bring part of the grain: for a city of 150,000, 95% of it keeps the haul within a day.

In history

When Francisco de Orellana came down the Amazon in 1541 and 1542, he reported densely peopled banks for hundreds of kilometres, and his chaplain Gaspar de Carvajal wrote of fortified towns and roads. For four centuries scholars dismissed them. Upstream of present-day Manaus lived the Omagua, perhaps 60,000 people around 1500 by John Hemming's estimate, who wove and painted cloth that they traded with their neighbours. In 1639 Pedro Teixeira counted more than 400 of their villages; fifty years later Samuel Fritz found 38, many moved onto islands for safety. In between came epidemics: smallpox alone, in 1648, may have killed up to a third of them.

At the river's mouth, on Marajó island, the Marajoara culture flourished from about AD 800 to 1400. Its people raised their villages on earthen mounds, partly built over natural rises, because the low ground flooded every rainy season. One of the largest sites, Os Camutins, had 40 mounds and perhaps 10,000 people. They ate mostly seeds, palm fruit such as açaí, and small fish taken in the dry months. Marajó has no hard stone, so stone for axes was traded in. Across the basin, farmers made dark soils, terra preta, from charcoal, bones, broken pottery and manure.

How large a city?

Living there

Its woods spare enough to burn: about 3,500 tonnes of wood a year for its hearths and workshops. Provisional figure.

Its market sells grain, rice, flax, cotton and sugar cane, and buys iron and salt. About 110 market towns stand in its countryside.

About 30% of what its people eat does not come from the fields. Of that share: herds 33%, fish 35%, gardens 33%. That is some 2,200 livestock units on 32 km² of pasture, and about 510 fishers in 130 boats. Hearth estimate.

What makes it hard

• Every rainy season the river covers the low ground. Houses, graves and stores sit on raised mounds, and the mounds must be patched and kept up with fresh fill.
• Fishing follows the water. In the dry months fish are trapped in shrinking streams and pools and easy to take; in the rainy season the same methods bring in far less.
• Forest soil is poor: cleared land yields for a few years, then rain and floods wash it out and the fields must move. Only soil enriched over generations with charcoal and refuse keeps a town in one place.
• The river brings strangers, and strangers bring disease. One smallpox epidemic on the Amazon, in 1648, lasted three months and may have killed up to a third of a people.
• A floodplain has no hard rock. Every stone axe and blade must be traded in from elsewhere.

Hard years

About one year in 8, the harvest falls below four fifths of a normal one: the town is short of some 1,400 of the 4,700 tonnes of grain its land gives it, and the water lets it bring the gap in. A plague that kills 39% of the town, as the Black Death did in Europe's towns, would leave about 3,100 km² of its fields idle.

What it can make

Grain, Rice, Flax, Cotton, Sugar cane, Spices, Dye plants, Orchards, Herbs, Maize, Horses (at a cost), Cattle and hides, Cheese, Pigs and bacon, Goats, Honey and wax, Silk, Ivory, Timber, Charcoal, Fish, Shipyards

What it lives on

Yams and other tubers, Rice

Underground

What a city digs depends on the rock under it: Granite, Volcanic rock, Ultramafic rock (peridotite, serpentinite), Schist and gneiss, Marble, Limestone and chalk, Sandstone, shale and clay, Salt beds, River gravels and sands

Found here

Gathered (Rerum): Açaí Berry, Açaí Palm Heart, Activated Charcoal, African Buffalo Hide, African Buffalo Meat, Beeswax Block, Beetle Wing, Brazil Nut Pod

Hear it

• The town: City in the Jungle (album RPG Ambiences Vol. 8)
• The market: Medieval Village Marketplace (on Patreon, Guardian tier)
• The quays: Medieval Harbor District (on Patreon, Guardian tier)
• The countryside: Walking in a Jungle (on Patreon, Guardian tier)

Tropical Rainforest in Biomes: plants, animals, hazards and sounds

The same climate

A town in the tropical rainforest, A town in the tropical rainforest, on the coast

By city size

1,000, 3,000, 10,000, 30,000, 100,000, 300,000, 1,000,000

Sources

• Wikipedia contributors, Gaspar de Carvajal, Wikipedia, The Free Encyclopedia, 2026. en.wikipedia.org
• Wikipedia contributors, Omagua people, Wikipedia, The Free Encyclopedia, 2026. en.wikipedia.org
• Wikipedia contributors, Marajoara culture, Wikipedia, The Free Encyclopedia, 2026. en.wikipedia.org
• Wikipedia contributors, Terra preta, Wikipedia, The Free Encyclopedia, 2026. en.wikipedia.org

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