The population of Britain may have decreased by between 1.5 and 3 million after the Roman period, perhaps caused by environmental changes or by plague and smallpox (around 600, the smallpox spread from India into Europe).
The population of Britain may have decreased after the Roman period by between 1.5 and 3 million. This reduction may have been caused by environmental changes or by plague and smallpox (around 600 AD, the smallpox spread from India into Europe).