Simplify the following text for a Grade 9 native English-speaking person.
Original: The Black Death , an epidemic of bubonic plague that spread over the whole of Europe , arrived in England in 1348 and killed as much as a third to half the population .
Simplified: The Black Death , an epidemic that spread over all of Europe and parts of Asia , arrived in England in 1349 and killed perhaps up to a third of the population .