Trade

_{Focus Areas · Design document §3}

Available from: SO04 (Writing) or SO09 (Quipu)

14 breakthroughs — CORE 1 · STANDARD 6 · UNCOMMON 2 · RARE 1 · UNIQUE 4 — Primitive – Space

Builds on: Foraging (1) · Social Organization (7) · Animal Husbandry (2) · Metallurgy (1) · Mathematics (2) · Mechanics (1) · Chemistry (1) · Quintessic Physics (1) · Energy Systems (4)

Leads into: Stonework (1) · Social Organization (1) · Metallurgy (1) · Seafaring (1) · Philosophy and the Arts (1) · Textiles & Materials (1) · Water Management (2)

_{The numbers count prerequisite links between this focus and the other. How to read the tables.}

Overview

ID	Breakthrough	Tier	Era	Prerequisites
TR01	Barter System	STANDARD	Primitive	SO01 (Basic Counting)
TR02	Currency	CORE	Ancient	SO04 + ME01 (Copper Working)
TR03	Caravansary	STANDARD	Ancient	TR02 + (AH02 or AH05)
TR05	Letter of Credit	STANDARD	Medieval	TR02 + SO04 + SO11 (Banking — the houses that honoured the bill)
TR06	Joint Stock Company	STANDARD	Early Modern	TR05 + SO11 (Banking)
TR08	Cowrie Shell Currency	UNIQUE	Ancient	TR01 + Coastal location
TR09	Free Trade Agreements	STANDARD	Modern	TR06 + SO06 (Codified Law)
TR10	Futures Market	UNCOMMON	Modern	TR05 + MA06 (Probability Theory — insurance) + MA09 (Statistics)
TR11	Caravan Oasis Network	UNIQUE	Ancient	TR03 (Caravansary) + Desert/arid biome
TR12	Potlatch Economy	UNIQUE	Ancient	TR01 + G01 + Coastal/forest biome
TR14	Bazaar Economy	UNIQUE	Classical	TR01 + SO06 (Codified Law) + Desert/arid or Many neighbors biome
TR15	Post-Scarcity Economics	RARE	Space	MC12 (Robotics) + (ES08 Fusion, or ES12 Zero-Point, or ES14 Adv. Fission, or QM-E05 Re-Tempering Reactor, or QM-E07 Aether Tension Engine)
TR16	Phase Exchange	UNCOMMON	Modern	CH22 (Five-Phase Theory) + TR05 (Letter of Credit)
TR17	Long-Distance Trade	STANDARD	Classical	TR03 (Caravansary) + TR02 (Currency)

Prerequisite map

flowchart LR
  n_TR01["TR01 Barter System"]:::STANDARD
  n_TR08["TR08 Cowrie Shell Currency"]:::UNIQUE
  n_TR12["TR12 Potlatch Economy"]:::UNIQUE
  n_TR14["TR14 Bazaar Economy"]:::UNIQUE
  n_TR02["TR02 Currency"]:::CORE
  n_TR03["TR03 Caravansary"]:::STANDARD
  n_TR11["TR11 Caravan Oasis Network"]:::UNIQUE
  n_TR17["TR17 Long-Distance Trade"]:::STANDARD
  n_TR05["TR05 Letter of Credit"]:::STANDARD
  n_TR06["TR06 Joint Stock Company"]:::STANDARD
  n_TR09["TR09 Free Trade Agreements"]:::STANDARD
  n_TR10["TR10 Futures Market"]:::UNCOMMON
  n_TR16["TR16 Phase Exchange"]:::UNCOMMON
  n_TR15["TR15 Post-Scarcity Economics"]:::RARE
  n_TR02 --> n_TR03
  n_TR02 --> n_TR05
  n_TR05 --> n_TR06
  n_TR01 --> n_TR08
  n_TR06 --> n_TR09
  n_TR05 --> n_TR10
  n_TR03 --> n_TR11
  n_TR01 --> n_TR12
  n_TR01 --> n_TR14
  n_TR05 --> n_TR16
  n_TR03 --> n_TR17
  n_TR02 --> n_TR17
  classDef CORE fill:#dbeafe,stroke:#1d4ed8,color:#0b1b3b
  classDef STANDARD fill:#f1f5f9,stroke:#64748b,color:#0f172a
  classDef UNCOMMON fill:#dcfce7,stroke:#15803d,color:#052e16
  classDef RARE fill:#fef3c7,stroke:#b45309,color:#3b2005
  classDef UNIQUE fill:#fae8ff,stroke:#a21caf,color:#3b0a3f

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_{Prerequisites within this focus. Box colour is the tier (blue CORE, grey STANDARD, green UNCOMMON, amber RARE, purple UNIQUE); dotted arrows are alternatives (“or”); a line can pass behind another box, so follow it from its start. 11 of these 14 breakthroughs also need breakthroughs from other foci, which the overview above lists.}

Breakthroughs

TR01 · Barter System

• Tier: STANDARD · Era: Primitive
• Prerequisites: SO01 (Basic Counting)
• Unlocks: ⟨[+1 Gold] from each Trade Route⟩ — city connections begin to pay the moment roads exist. The Trade screen (UI).
• Leads to: S10 Obsidian Trade Empire, SF16 Dhow Monsoon Trading, TR08 Cowrie Shell Currency, TR12 Potlatch Economy, TR14 Bazaar Economy, TX12 Imperial Dye Mastery

TR02 · Currency

• Tier: CORE · Era: Ancient
• Prerequisites: SO04 + ME01 (Copper Working)
• Unlocks: Market (and the Arabian Bazaar). Standard coin, standard price.
• Leads to: SO11 Banking, ME17 Assaying, TR03 Caravansary, TR05 Letter of Credit, TR17 Long-Distance Trade

TR03 · Caravansary

• Tier: STANDARD · Era: Ancient
• Prerequisites: TR02 + (AH02 or AH05)
• Unlocks: Caravansaryⁿ [45/1; +1 Gold; ⟨[+1 Gold] from each Trade Route⟩; ⟨[+1 Gold] from [Desert] tiles [in this city]⟩].
• Leads to: TR11 Caravan Oasis Network, TR17 Long-Distance Trade, WM11 Industrial Canal Network

TR05 · Letter of Credit

• Tier: STANDARD · Era: Medieval
• Prerequisites: TR02 + SO04 + SO11 (Banking — the houses that honoured the bill)
• Unlocks: ⟨[+25]% [Gold] from Trade Routes⟩ — value travels without the coin.
• Leads to: CU07 Renaissance, TR06 Joint Stock Company, TR10 Futures Market, TR16 Phase Exchange

TR06 · Joint Stock Company

• Tier: STANDARD · Era: Early Modern
• Prerequisites: TR05 + SO11 (Banking)
• Unlocks: Trading Companyⁿ [375/3; requires a Bank in this city; +3 Gold; Merchant ×2; ⟨[+2 Gold] from each Trade Route⟩].
• Leads to: TR09 Free Trade Agreements, WM11 Industrial Canal Network

TR08 · Cowrie Shell Currency

• Tier: UNIQUE · Era: Ancient
• Prerequisites: TR01 + Coastal location
• Unlocks: Cowrie Exchangeⁿ [replaces Market; 100/0; +2 Gold; Gold +25%; Merchant ×1; ⟨[+1 Gold] from [Coast] tiles [in this city]⟩] — satisfies Currency's Copper Working prerequisite. Civ unique: ⟨[+1 Gold] from [Coast] tiles [in all cities]⟩ — money you can pick up on the beach.
• Notes: West African/South Asian/Chinese alternative economic path.

TR09 · Free Trade Agreements

• Tier: STANDARD · Era: Modern
• Prerequisites: TR06 + SO06 (Codified Law)
• Unlocks: Stock Exchange; ⟨Enables Research agreements⟩ (the canonical unique) — treaties that trade knowledge as well as goods.

TR10 · Futures Market

• Tier: UNCOMMON · Era: Modern
• Prerequisites: TR05 + MA06 (Probability Theory — insurance) + MA09 (Statistics)
• Unlocks: Commodity Exchangeⁿ [625/3; requires a Bank in this city; +4 Gold; ⟨[+1 Gold] from [Strategic resource] tiles [in this city]⟩].

TR11 · Caravan Oasis Network

• Tier: UNIQUE · Era: Ancient
• Prerequisites: TR03 (Caravansary) + Desert/arid biome
• Unlocks: Grand Caravanseraiⁿ [replaces Caravansary; 40/1; +1 Gold; ⟨[+2 Gold] from each Trade Route⟩; ⟨[+1 Food, +1 Gold] from [Oasis] tiles [in this city]⟩]; Oasis Rest Stopⁿ [improvement on Desert; 4 turns; +1 Food, +1 Gold]. Civ unique: ⟨[+1 Gold] from [Desert] tiles [in all cities]⟩ — the empty land is a road with tolls.
• Notes: Silk Road, Trans-Saharan trade, Arabian caravanserai.

TR12 · Potlatch Economy

• Tier: UNIQUE · Era: Ancient
• Prerequisites: TR01 + G01 + Coastal/forest biome
• Unlocks: Potlatch Hallⁿ [replaces Monument; 40/1; +2 Culture, +1 Happiness; Great Merchant points 2]. Civ unique: ⟨[+1] Happiness from each type of luxury resource⟩ — wealth given away comes back as standing.
• Notes: Pacific Northwest indigenous economic tradition.

TR14 · Bazaar Economy

• Tier: UNIQUE · Era: Classical
• Prerequisites: TR01 + SO06 (Codified Law) + Desert/arid or Many neighbors biome
• Unlocks: Soukⁿ [replaces Market; 100/0; +2 Gold; Gold +25%; Merchant ×2]. Civ unique: ⟨[+10]% [Gold] from Trade Routes⟩ and ⟨[+1] Happiness from each type of luxury resource⟩ — a market that thrives on variety. (Arabia's Bazaar remains Arabian.)
• Notes: Islamic/Persian/Central Asian bazaar culture.

TR15 · Post-Scarcity Economics

• Tier: RARE · Era: Space
• Prerequisites: MC12 (Robotics) + (ES08 Fusion, or ES12 Zero-Point, or ES14 Adv. Fission, or QM-E05 Re-Tempering Reactor, or QM-E07 Aether Tension Engine)
• Unlocks: ⟨[-100]% maintenance cost for [All] buildings [in all cities]⟩; ⟨[+3 Happiness] [in all cities]⟩ — scarcity ends, and with it the bill.
• Notes: Speculative endgame.

TR16 · Phase Exchange

• Tier: UNCOMMON · Era: Modern
• Prerequisites: CH22 (Five-Phase Theory) + TR05 (Letter of Credit)
• Unlocks: Phase Exchangeⁿ [500/3; +3 Gold; ⟨[+2 Gold] from each Trade Route⟩]. Process only: routes that complete a cycle pay more; stacks toward Full-Cycle Coupling (QM-E11). Also discoverable through Chemistry.
• Notes: A route that turns the wheel.

TR17 · Long-Distance Trade

• Tier: STANDARD · Era: Classical
• Prerequisites: TR03 (Caravansary) + TR02 (Currency)
• Unlocks: Petra (world wonder); Trading post (improvement) — the routes that cross a continent.
• Notes: The Silk Road opens (c. 130 BC).