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# Sumer

## Overview
Sumer was the earliest known civilization in southern Mesopotamia (modern-day southern Iraq), emerging ~4500 BCE and flourishing during the 3rd millennium BCE. It is credited with foundational innovations including writing (cuneiform), urbanization, and codified law. @t[~4500 BCE]

## Key Facts
- Region: Southern Mesopotamia, between the Tigris and Euphrates rivers <!-- reviewed:2026-02-23 -->
- Period: ~4500–1900 BCE @t[4500 BCE..1900 BCE] <!-- reviewed:2026-02-23 -->
- Major cities: Ur, Uruk, Eridu, Lagash, Nippur, Kish <!-- reviewed:2026-02-23 -->
- Language: Sumerian (language isolate) <!-- reviewed:2026-02-23 -->
- Writing system: Cuneiform, developed ~3400 BCE @t[~3400 BCE] <!-- reviewed:2026-02-23 -->
- Government: City-states ruled by *lugal* (kings) and *ensi* (governors) <!-- reviewed:2026-02-23 -->

## Major Periods
- Ubaid period (~5500–4000 BCE): Proto-urban settlements @t[5500 BCE..4000 BCE] <!-- reviewed:2026-02-23 -->
- Uruk period (~4000–3100 BCE): First true cities, invention of writing @t[4000 BCE..3100 BCE] <!-- reviewed:2026-02-23 -->
- Early Dynastic period (~2900–2350 BCE): Competing city-states @t[2900 BCE..2350 BCE] <!-- reviewed:2026-02-23 -->
- Third Dynasty of Ur (~2112–2004 BCE): Final Sumerian renaissance under Ur-Nammu @t[2112 BCE..2004 BCE] <!-- reviewed:2026-02-23 -->

## Achievements
- Invented cuneiform writing ~3400 BCE @t[~3400 BCE] [^1] <!-- reviewed:2026-02-23 -->
- Built ziggurats as temple complexes <!-- reviewed:2026-02-23 -->
- Developed the sexagesimal (base-60) number system <!-- reviewed:2026-02-23 -->
- Created the earliest known legal code (Code of Ur-Nammu, ~2100 BCE) @t[~2100 BCE] <!-- reviewed:2026-02-23 -->
- Established irrigation agriculture at scale, initially enabled by predictable tidal surges from the Persian Gulf before large-scale canal systems were required <!-- reviewed:2026-02-23 -->
- Produced the *Epic of Gilgamesh*, among the earliest literary works @t[~2100 BCE] [^2] <!-- reviewed:2026-02-23 -->

## Decline
Sumer was absorbed by the Akkadian Empire under Sargon of Akkad ~2334 BCE, briefly revived under the Third Dynasty of Ur, and finally eclipsed by the rise of Babylon ~1900 BCE. @t[~2334 BCE]

## Environmental Foundations
Recent research (2025) has revised understanding of how Sumer's agriculture and urbanization emerged. Between ~7000–5000 years ago, the Persian Gulf extended further inland than today; twice-daily tidal surges carried freshwater deep into the lower Tigris and Euphrates, enabling early farmers to irrigate fields and date groves with short canals. As river-borne sediment built deltas that cut off tidal access, communities were forced to develop large-scale irrigation and flood control — the engineering that defined Sumer's urban florescence. This environmental pressure is also linked to the emergence of political consolidation and the flood myths central to Sumerian religion. [^3]

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[^1]: Schmandt-Besserat, D. *Before Writing* (1992)
[^2]: George, A. *The Epic of Gilgamesh* (Penguin Classics, 2003)
[^3]: Giosan, L. & Goodman, R. "Morphodynamic Foundations of Sumer." *PLOS ONE* 20(8): e0329084 (2025). Woods Hole Oceanographic Institution / Lagash Archaeological Project (Penn Museum).