The 4.2-Kiloyear Event: Megadrought and the Collapse of the Akkadian Empire and Egyptian Old Kingdom
- Date
- c. 2200 BCE
- Category
- Environment & climate
- Region
- Middle East, North Africa, and South Asia
- Era
- Ancient Civilizations
- Significance
Around 2200 BCE a severe, century-long aridification known as the 4.2-kiloyear event spread across the Mediterranean, West Asia, North Africa and South Asia, ranking among the most abrupt climate shocks of the Holocene.
Driven by a weakening of the Atlantic meridional overturning circulation, a southward shift of the Intertropical Convergence Zone and a faltering Indian summer monsoon, it produced collapsing Nile floods, dust storms and crop failures across the ancient Near East. The drought is widely linked to the synchronous downfall of the world's first empire, the Akkadian Empire of Mesopotamia, whose northern agricultural plains were abandoned as refugees fled south, as well as the disintegration of Egypt's Old Kingdom into the fragmented First Intermediate Period. It simultaneously stressed the Indus Valley civilisation, contributing to the de-urbanisation of its great cities, and disrupted Early Bronze Age settlements in Anatolia, the Aegean and the Levant. So profound was its global signature, recorded in stalagmites, lake sediments and ice cores, that geologists in 2018 chose it to define the base of the Meghalayan Age, the current and final subdivision of the Holocene, with a Global Stratotype Section and Point in Mawmluh Cave, India, dated to roughly 4,250 calibrated years before present.
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Empires active in c. 2200 BCE
- Akkadian Empire2334 BCE – 2154 BCE
- Indus Valley (Harappan) Civilization2600 BCE – 1900 BCE
- Bactria-Margiana Archaeological Complex (Oxus Civilization)2250 BCE – 1700 BCE
- Egyptian Old Kingdom2686 BCE – 2181 BCE
- Elamite Kingdom2700 BCE – 539 BCE
Related environment & climate events
- Decline and De-urbanisation of the Indus Civilisationc. 1900 BCE
- Eruption of Thera (Santorini)c. 1600 BCE (debated)
- The Pleistocene–Holocene boundary and the start of the Holocenec. 11,700 years ago (c. 9700 BCE)
- End of the African Humid Period and Desertification of the Saharac. 3500–2700 BCE
- Eruption of Vesuvius buries Pompeii and Herculaneum79 CE (traditionally 24 August)
- Late Pleistocene megafaunal extinctions and the overkill-vs-climate debatec. 15,000 – 10,000 years ago
Further reading
The wider story
A New Green History of the World
The classic accessible account of how environment and climate have shaped human history.
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