A crowd of strangers
Around 3100 BCE, the Mesopotamian site of Uruk may have held as many as 50,000 residents, with tens of thousands more in its surroundings, according to estimates that are hedged in the literature. If so, most people there lived among others they had never met. That is a new social situation for a species whose earlier communities, for most of history, were small. Why would anyone choose it?
There is no single answer, and cities did not begin in one place. UNESCO and other sources describe urban centres emerging in Mesopotamia, the Indus region, China, the Andes, Mesoamerica and Africa, at different times and in different forms.
What counts as a city?
The archaeologist V. Gordon Childe proposed in 1950 a ten-point model of an “urban revolution”. Its features include dense settlements, specialist workers who did not farm, a surplus collected from farmers as tax or tithe, monumental buildings, a ruling class, writing and mathematics, long-distance trade, and a state organized by residence rather than kinship. Scholars generally agree that Childe identified a major transformation, but modern models of complex societies have moved beyond his list. His model also describes the shift from farming villages to state-level societies, not the exact moment a settlement becomes a city.
The definition matters because it determines what is left out. At Göbekli Tepe, hunter-gatherers raised monumental pillars before farming took hold, and at Çatalhöyük closely packed houses, with no streets and little difference in size, were occupied for more than two thousand years. Neither fits Childe’s checklist neatly. The article on farming explains some of what made large settlements possible.
Many routes to urban life
The grouping below is a rough aid, not a scholarly classification, and many sites fit more than one.
Dense river-valley centres
Uruk in southern Iraq reached about 250 hectares by 3100 BCE. Mohenjo-daro, in the Indus valley, dates to the third millennium BCE and had a citadel, a lower town on a street grid, wells and drainage. Only about a third of its 240 hectares had been excavated when UNESCO assessed it.
Monumental planned centres
Caral, in Peru’s Supe valley, developed between about 3000 and 1800 BCE with platform mounds and sunken courts. Liangzhu, in China, c. 3300 to 2300 BCE, had a water-control system and graded cemeteries. Teotihuacan in Mexico covered 36 square kilometres, with at least 25,000 residents, between the first and seventh centuries CE.
Trade-linked towns in Africa
Djenné-Djeno in the inland Niger delta was inhabited from about the third century BCE and linked to trade. Great Zimbabwe, built between about 1100 and 1450 CE, held more than 10,000 people at its height and yielded beads and ceramics from as far as China and Persia.
Placing Africa’s cities late in a list can suggest they were a delayed copy of earlier ones. The record shows something different: urban life took multiple forms, built from local materials and local economies. Great Zimbabwe also shows how myths can distort understanding. UNESCO notes that stories linking the site to the Queen of Sheba or a biblical origin come from persistent legends, not evidence.
What cities changed
- Specialization. People could make a living as potters, builders, scribes, traders or priests without farming.
- Exchange. Markets and long-distance routes brought materials, goods and ideas together.
- Institutions. Officials, temples and courts organized labour, storage and conflict.
- Surplus extraction. Part of what farmers produced flowed to rulers and institutions, which concentrated wealth.
- Shared risk. Density made it easier to spread both knowledge and disease, and to depend on distant harvests.
Childe’s model includes surplus collected from farmers as tax or tithe and a ruling class that absorbed much of it. That is one way of describing inequality, and it did not appear to the same degree in every city. For disease, evidence from early farming settlements such as Çatalhöyük suggests that crowding was linked with health costs, and concentrated populations are a plausible but not universally measured factor in cities. City dwellers also relied on food from outside their walls, which made them sensitive to drought or conflict.
Cities were rarely permanent. Teotihuacan was razed by fire and abandoned in the seventh century CE, and Uruk was abandoned around 700 CE. Great Zimbabwe was left around 1450; one suggested reason is food shortage and deforestation, but this is a likely explanation, not a proven one. Abandonment shows that urban life is a way of living that communities took up, adapted and sometimes left behind.
Why this still matters
Most people today live in towns and cities, so the question of what a crowd of strangers needs from each other is not just ancient. Early cities show that people can build shared spaces, rules and trade networks beyond kinship, a theme also found in why humans need to belong. They also show that those arrangements could be unequal, fragile and unevenly shared. Looking at cities across continents makes it harder to assume that there is one path toward “civilization”, and easier to see a range of experiments in living together.
