Between 1347 and 1352, a mysterious disease ravaged Europe, killing an estimated 25 million people -- 30 percent to 50 percent of the population.
At the time, people said the disease was caused by a peculiar conjunction of the planets, by a miasma stirred up by earthquakes in Central Asia or by a conspiracy of Jews to undermine Christendom.
Many called it the wrath of God and expected the end of the world.
Although the pandemic now called the Black Death lasted no more than six years, according to most medieval historians, the disease behind it erupted periodically in different parts of Europe for the next three centuries, leaving millions more dead in its wake.
