The Black Death was a bubonic plague pandemic that devastated Europe from 1347 to 1352. Believed to have originated in Asia, it spread to Europe via trade routes, first arriving in Sicily in October 1347 from ships coming from the Black Sea region. The pandemic killed between 30% to 50% of Europe's population, with estimates of 25-50 million deaths. The plague was caused by the bacterium Yersinia pestis, spread by fleas carried by rats and through person-to-person transmission.