Estimates of the population of ancient Greece are very rough approximations. Population figures are scarce and incomplete, and most existing records involve taxes or military service, which applied only to adult male citizens. Statistics for women, children, foreign residents, and slaves—the people who made up a large portion of the population—simply do not exist. Even for Athens, which provided a more complete picture than any other city-state*, population figures are merely estimates.
Attica, the region in which Athens was located, may have had a population of more than 100,000 citizens during most of the classical* period. At the beginning of the Peloponnesian War in 431 B.C., the population of Attica—including women, children, slaves, and foreigners—totaled more than 300,000 people. The city-state of Argos had about the same number of citizens, although fewer slaves and foreigners, and Corinth had fewer than half that number. The Greek colonies on the island of Sicily may have had a population as high as 750,000 people.
Because all adult male Roman citizens were required to register for the census, more complete population figures are available for Rome. These figures suggest that there were about 120,000 adult male Roman citizens in the 400s B.C. This rose to about 300,000 two centuries later. As the Roman empire expanded, and certain conquered peoples received Roman citizenship, the population increased accordingly. In 70 B.C., after citizenship was granted to all people of Italy south of the Po River, the figure reached 900,000.
A census of the empire conducted by the emperor Augustus in 28 B.C. put the figure at about 4 million citizens. In the first century A.D., the city of Rome had about a million inhabitants, and the total population of the Roman empire is estimated to have been more than 50 million people. (See also Census, Roman; Greece, History of; Rome, History of.)
* city-state independent state consisting of a city and its surrounding territory
* classical in Greek history, refers to the period of great political and cultural achievement from about 500 B.C. to 323 B.C.