World Power Data Methodology
The "World Power" visualization shows the estimated share of global economic output (GDP) controlled by different power blocs throughout history. This page explains our data sources and methodology.
Modern Era (1750-2025)
Primary Source: Maddison Project Database
For 1750 onwards, GDP estimates come from the Maddison Project Database, which provides PPP-adjusted GDP estimates based on extensive economic historical research.
The Maddison Project continues Angus Maddison's pioneering work in historical national accounts, providing the most comprehensive and widely-cited source for long-run GDP comparisons.
Ancient & Medieval Eras (3500 BC - 1750 AD)
Important: Pre-1750 data represents rough estimates that should be treated as illustrative rather than definitive. These figures are approximations based on scholarly research but involve significant uncertainty.
For periods before 1750, we rely on a combination of scholarly sources:
Academic Sources
- Angus Maddison, "The World Economy: A Millennial Perspective" (OECD, 2001) - Provides GDP estimates back to 1 AD for major regions. OECD iLibrary
- Maddison Project Database - Historical GDP per capita data, especially strong post-1820. Maddison Project
- McEvedy & Jones, "Atlas of World Population History" (Penguin, 1978) - Population estimates from ancient times, widely cited in economic history
- Ian Morris, "The Measure of Civilization" (Princeton, 2013) - Social development index comparing East and West over 15,000 years. Princeton Press
- Broadberry, Guan & Li, "China, Europe and the Great Divergence" (Economic History Review, 2017) - Historical GDP comparisons. Wiley Online
- Walter Scheidel (ed.), "The Cambridge Companion to the Roman Economy" (2012) - Roman economic estimates. Cambridge Core
- Goldsmith, Raymond, "An Estimate of the Size and Structure of the National Product of the Early Roman Empire" (Review of Income and Wealth, 1984)
- Wilson, Andrew, "Quantifying Roman Economic Growth" in Bowman & Wilson eds. (2009)
- Pamuk & Shatzmiller, "Plagues, Wages, and Economic Change in the Islamic Middle East" (Journal of Economic History, 2014)
Data Quality Notes
The certainty of estimates decreases as we go further back in time:
- 1820-present: High confidence - based on national accounts and extensive records
- 1500-1820: Moderate confidence - based on trade records, tax data, and historical accounts
- 1-1500 AD: Lower confidence - based on archaeological evidence, population estimates, and fragmentary records
- Before 1 AD: Very approximate - primarily based on population and urbanization estimates
Estimation Approach
For ancient periods, economic "power" is estimated based on:
- Population - The primary driver of pre-modern economic output
- Urbanization rates - Indicator of economic complexity
- Archaeological evidence - Trade goods, infrastructure, agricultural output
- Historical records - Tax records, tribute payments, trade documentation
Power Bloc Definitions
Countries and regions are assigned to power blocs based on political control, economic integration, and military influence:
| Bloc | Description | Period |
|---|---|---|
| Mesopotamia | Sumerian, Akkadian, Babylonian, Assyrian civilizations (Tigris-Euphrates region) | 3500 BC - 539 BC |
| Egypt | Ancient Egypt under pharaonic rule (includes Ptolemaic period) | 3100 BC - 30 BC |
| Carthage | Phoenician/Carthaginian territories in North Africa and western Mediterranean | 814 BC - 146 BC |
| Persian Empire | Achaemenid, Parthian, Sassanid, Safavid empires | 550 BC - 1750 AD |
| Greek World | Greek city-states and Hellenistic kingdoms | 800 BC - 146 BC |
| Roman Empire | Roman Republic and Western Empire | 500 BC - 476 AD |
| Byzantine Empire | Eastern Roman Empire | 330 AD - 1453 AD |
| Islamic Caliphate | Umayyad and Abbasid caliphates | 632 AD - 1258 AD |
| Mongol Empire | Mongol Empire at peak extent | 1206 - 1368 AD |
| China | Various Chinese dynasties (Shang, Zhou, Han, Tang, Song, Ming, Qing, PRC) | 2000 BC - present |
| India | Indian subcontinent (Indus Valley, Maurya, Gupta, Mughal, etc.) | 2500 BC - present |
| Sub-Saharan Africa | African kingdoms south of Sahara (Kush, Axum, Ghana, Mali, Songhai, etc.) | All periods |
| Southeast Asia | Kingdoms of Southeast Asia (Khmer, Srivijaya, Majapahit, etc.) | All periods |
| Central Asia | Steppe peoples and kingdoms (Scythians, Xiongnu, Turks, etc.) | Ancient periods |
| Ottoman Empire | Ottoman territories | 1299 - 1922 AD |
Limitations & Caveats
- Pre-1 AD estimates are highly speculative - Very limited quantitative data exists
- GDP is anachronistic - Modern economic concepts don't map cleanly to pre-modern economies
- "Power" vs. GDP - Economic output doesn't perfectly correlate with political/military power
- Bloc boundaries are simplified - Real historical influence was more complex and overlapping
Contributing Corrections
If you have corrections or improvements based on scholarly sources, please open an issue on GitHub with citations.