Short answers, pulled from the story.
The Black Death pandemic occurred from 1346 to 1353. Evidence suggests that a sudden surge of deaths in what is today Kyrgyzstan began in the late 1330s, potentially predating the previously postulated 14th-century Mongol conquests.
In 1347, Genoese trading ships fleeing the siege of Kaffa introduced the plague into Europe via fleas on black rats. The disease then spread through the Mediterranean Basin to North Africa, West Asia, and the rest of Europe via Constantinople, Sicily, and the Italian Peninsula as pneumonic plague.
Definitive confirmation arrived in 2010 with a publication by Haensch et al. who used polymerase chain reaction techniques to demonstrate DNA presence of Yersinia pestis in human skeletons from mass graves across northern, central, and southern Europe. Further genetic evidence traces the source to the Tian Shan mountains in Kyrgyzstan.
The Black Death killed between 75 million and 200 million people in Eurasia according to some estimates. In Christian Europe alone, agents for Pope Clement VI calculated 23,840,000 deaths by 1351, accounting for a mortality rate of 31%.
In 1377, the city-state of Ragusa now Dubrovnik Croatia implemented a thirty-day isolation period for new arrivals from plague-affected areas. This isolation period was later extended to forty days and given the name quarantino from the Italian word for forty.