The Black Death, a pandemic of plague spread along trade routes from Asia, swept Europe between 1347 and 1351 after arriving at Mediterranean ports such as Messina. It killed an estimated third to half of Europe's population, hitting crowded urban quarters especially hard. In response, ports such as Venice and Ragusa (Dubrovnik) introduced the first systematic quarantines, isolating arriving ships and people for fixed periods, and cities imposed sanitary cordons.
It forged an enduring link in the urban imagination between density, filth and contagion, prompting some of the earliest public-health controls on movement and settlement that would shape later sanitary and planning thought.