The document summarizes the Black Death plague that hit Europe in the 14th century. It describes how the plague originated in China and was brought to Europe by infected rats on trading ships. Once in Europe, fleas spread the plague by biting both rats and humans. The plague killed over 25 million people in Europe over 5 years, representing around 33% of the population. It caused widespread societal impacts such as labor shortages as people died in large numbers.