Population peaked at the height of imperial power in the 2nd century, then after Crisis of the Third Century declined, at first gradually, then, with the sacks of Rome in the 5th and 6th centuries, catastrophically.
Population peaked at the height of imperial power in the 2nd century. Crisis of the Third Century declined with the sacks of Rome in the 5th and 6th centuries. This was at first gradually. This was catastrophically. This was then.