In order to understand how civilizations have evolved over time, it's useful to look at population growth and decline in different geographic areas.

Tertius Chandler's compilation of the population of cities throughout history, Four Thousand Years of Urban Growth: An Historical Census uses a wide variety of historical sources to locate approximate populations for the world's largest cities since 3100 BCE.

It's a daunting task to try to calculate how many people lived in urban centers prior to recorded history. Even though the Romans were the first to conduct a census, requiring every Roman man to register every five years, other societies were not as diligent about tracking their populations. Widespread plagues, natural disasters with a large loss of life and wars that decimated societies (from both the aggressor and the conquered points of view) often provide unfortunate clues to historians for a given population's size.

But with few written records, and very little uniformity among societies that may be hundreds of miles apart, trying to determine whether China's pre-modern era cities were more populous than India's, for instance, is no easy task.

Counting Pre-Census Population Growth

The challenge for Chandler and other historians is the lack of formal census-taking before the 18th century. His approach was to look at smaller pieces of data to try to create a clear picture of populations. This included examining travelers' estimates, data on the numbers of households within cities, the numbers of food wagons arriving in cities and the size of each city or state's military. He looked at church records and the loss of lives in disasters.

Many of the figures Chandler presented can only be considered rough approximations of the urban population, but most include the city and surrounding suburban or urbanized area.

What follows is a list of the largest city at each point in history since 3100 BCE. It lacks population data for many cities but does provide a list of the largest cities throughout time. By looking at the first and second lines of the table, we see that Memphis remained the largest city in the world from at least 3100 BCE to 2240 BCE when Akkad claimed the title.