city along the sea coast inhabited by Christians, most of them Genoese." He further stated, "We went down to its port, where we saw a wonderful harbor with about two hundred vessels in it, both ships of war and trading vessels, small and large, for it is one of the world's celebrated ports." In early 1318 Pope John XXII established a Latin Church diocese of Kaffa, as a suffragan of Genoa. The papal bull of appointment of the first bishop attributed to him a vast territory: "a villa de Varna in Bulgaria usque Sarey inclusive in longitudinem et a mari Pontico usque ad terram Ruthenorum in latitudinem" ("from the city of Varna in Bulgaria to Sarey inclusive in longitude, and from the Black Sea to the land of the Ruthenians in latitude"). The first bishop was Fra' Gerolamo, who had already been consecrated seven years before as a missionary bishop ad partes Tartarorum. The diocese ended as a residential bishopric with the capture of the city by the Ottomans in 1475. Accordingly, Kaffa is today listed by the Catholic Church as a titular see. The new diocese effectively broke up the diocese of Khanbaliq, which functioned as one diocese for all Mongol territory from the Balkans to China. It is believed that the devastating pandemic of the Black Death entered Europe for the first time via Kaffa in 1347, through the movements of the Golden Horde. After a protracted siege during which the Mongol army under Janibeg was reportedly withering from the disease, they catapulted the infected corpses over the city walls, infecting the inhabitants, in one of the first cases of biological warfare. Fleeing inhabitants may have carried the disease back to Italy, causing its spread across Europe. However, the plague appears to have spread in a stepwise fashion, taking over a year to reach Europe from Crimea. Also, there were a number of Crimean ports under Mongol control, so it is unlikely that Kaffa was the only source of plague-infested ships heading to Europe. Additionally, there were overland caravan routes from the East that would have been carrying the disease into Europe as well. Kaffa eventually recovered. The thriving, culturally diverse city and its thronged slave market have been described by the Spanish traveler Pedro Tafur, who was there in the 1430s. In 1462 Caffa placed itself under the protection of King Casimir IV of Poland. However, Poland