The Siege of Caffa was a 14th-century military encounter when Jani Beg of the Golden Horde sieged the city of Caffa, between two periods in the 1340s. The city of Caffa, a Genoese colony, was a vital trading hub located in Crimea. The city was then part of Gazaria, a group of seven ports located in Crimea and belonging to the maritime empire of the Republic of Genoa. The event is historically significant primarily because it is believed to be one of the earliest instances of biological warfare.