For the lands around the Mediterranean Sea and their hinterlands, the period from the second millennium BCE to the early first millennium CE was one of substantial population growth. What would become the territory of the Roman Empire saw an average annual population growth of about 0.1 per cent from the 12th century BCE to the 3rd century CE, resulting in a quadrupling of the region's total population. Growth was slower around the eastern Mediterranean, which was already more developed at the beginning of the period, on the order of about 0.07 per cent per year. This was stronger growth than that seen in the succeeding period; from about 200 CE to 1800 CE, the European half of the empire only saw about 0.06 to 0.07 per cent annual growth (Europe as a whole saw 0.1 per cent annual growth rates), and the north African and west Asian parts of the empire saw almost no growth at all.
By comparison, what is now the territory of China experienced 0.1 per cent annual growth from 1 CE to 1800 CE. After population decline following the disintegration of the western half of the Roman state in the fifth and sixth centuries, Europe probably re-attained Roman-era population totals in the twelfth and thirteenth centuries and, following another decline associated with the Black Death, consistently exceeded them after the mid-15th century.
There are no reliable surviving records for the general demography of the Roman Empire. There are no detailed local records, such as underlie the demographic study of early modern Europe, either. Large numbers of impressionistic, moralizing, and anecdotal observations on demography survive from the literary sources. They are of little use in the study of Roman demography, which tends to rely instead on conjecture and comparison, rather than records and observations.