During the period of 1189-1485 in Medieval Britain, the population faced many threats including uprisings, invasions, civil wars, and raids. One of the greatest threats was the Black Death plague which arrived in Britain in 1348 from Asia via trade routes. It is estimated that the plague killed around one-third to one-half of the British population. While devastating, the plague did have some positive impacts by decreasing population size which relatively improved life and increased wealth as there were fewer mouths to feed.