A town in the flooded grassland

With what grows here (rice, pulses), this land can feed a town of about 38,000 people from farms less than a day's cart from its walls, about the size of Cologne around 1300.

Build a town in the flooded grassland

A town of 10,000 here

Its grain comes from 13 km around, 1 day by cart (comfortable). About 280 villages and 79,000 country people farm it, and the town keeps about 40 scholars. Grown to 40,000 people, its grain comes from 26 km around, 1.5 days by cart (strained). Grown to 150,000 people, its grain comes from 50 km around, 2 days by cart (strained). A city of 1,000,000 cannot live off this land alone.

In history

In the Llanos de Mojos of Bolivia, savannahs that flood every rainy season, the Casarabe culture flourished from about AD 500 to 1400. Lidar surveys published in 2022 revealed two large towns of 147 and 315 hectares, with platforms and earthen pyramids up to 22 m tall, ringed by banks and tied to smaller villages by straight raised causeways several kilometres long. Canals and reservoirs managed the water. These were not empty ceremonial centres: people lived there all year, grew maize as their staple and got their meat from hunting and fishing.

In England's Fens, before the great drainage, fields were possible only on the fen islands and the silt ground around the Wash; the rest was pasture, fishing, fowling, and reed and sedge for thatch. Ely stood on such an island, and Bede explained its name by the many eels caught in the marshes. In 1086 the village of Stuntenei was worth 24,000 eels to the abbot of Ely, and peat cut as turf was the fuel. When investors began draining the Great Level for Charles I in the 1630s, fenmen who lived by fish and fowl, the "Fen Tigers", sabotaged the works.

How large a city?

Living there

There are no woods to spare here. The town needs about 6,200 tonnes of wood a year for its hearths and workshops: it burns straw (about 8,000 tonnes a year), dung and brush, and buys the rest. Provisional figure.

Its market sells grain, rice, flax, cotton and sugar cane, and buys timber, iron and salt. About 7 market towns stand in its countryside.

About 20% of what its people eat does not come from the fields. Of that share: herds 35%, gardens 65%. That is some 1,500 livestock units on 23 km² of pasture. Hearth estimate.

What makes it hard

• Every rainy season the plain becomes a sheet of water. Houses, granaries and roads must stand on raised ground, and the earth for them is dug from the ditches around.
• Only the high spots can be ploughed. Most of the land is for grazing, fishing, fowling and cutting reeds, so the town's grain is short and its rents may be paid in eels.
• Winter brings the water from the hills: when the rivers coming down from the uplands overflow, the low ground goes under.
• Draining the marsh makes enemies of everyone who lives off it: fishers and fowlers can wreck the works, as the Fen men did.

Hard years

About one year in 8, the harvest falls below four fifths of a normal one: the town is short of some 660 of the 2,300 tonnes of grain its land gives it, with no water to bring the gap in. A plague that kills 39% of the town, as the Black Death did in Europe's towns, would leave about 200 km² of its fields idle.

What it can make

Grain, Rice, Flax, Cotton, Sugar cane, Dye plants, Orchards, Herbs, Potato, Maize, Wool (at a cost), Horses (at a cost), Cattle and hides, Cheese, Pigs and bacon (at a cost), Goats, Honey and wax, Silk

What its land cannot give, a town here must buy: timber.

What it lives on

Rice, Pulses

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): African Wild Rice, Wild Rice Straw, American Alligator Meat, Antelope Grass Grain, Beetle Wing, Bourgou Seeds, Bourgou Stem, Buriti Fibre

Hear it

• The town: Fantasy Medieval City (album RPG Ambiences Vol. 6)
• The market: Medieval Village Marketplace (on Patreon, Guardian tier)
• The countryside: Farmyard with People and Animals (on Patreon, Guardian tier)

Flooded Grassland in Biomes: plants, animals, hazards and sounds

The same climate

A town in the flooded grassland, on a river, A town in the flooded grassland, on the coast

By city size

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

Sources

• Heiko Prümers, Carla Jaimes Betancourt, José Iriarte, Mark Robinson, Martin Schaich, Lidar reveals pre-Hispanic low-density urbanism in the Bolivian Amazon, Nature 606, 325-328, 2022. www.nature.com
• Wikipedia contributors, The Fens, Wikipedia, 2026. en.wikipedia.org
• Wikipedia contributors, Ely, Cambridgeshire, Wikipedia, 2026. en.wikipedia.org

Open the city builder — MGS Toolbox