Jani Beg (, ), also known as Djanibek Khan, was a Khan of the Golden Horde from 1342 to 1357, succeeding his father Öz Beg Khan. Reign With the support of his mother Taydula Khatun, Jani Beg made himself khan after eliminating his older brother and rival Tini Beg at Saray-Jük in 1342; he had already killed another ambitious brother, Khiḍr Beg. He is known to have actively interfered in the affairs of Rus principalities and of Lithuania. The Grand Princes of Moscow, Simeon Gordiy and Ivan II were under constant political and military pressure from Jani Beg. Jani Beg commanded a massive Crimean Tatar force that attacked the Crimean port city of Kaffa in 1343. The siege was lifted by an Italian relief force in February. In 1345 Jani Beg again besieged Kaffa; however, his assault was again unsuccessful due to an outbreak of the Black Plague among his troops. Jani Beg's army catapulted infected corpses into Kaffa in an attempt to use the Black Death to weaken the defenders. Infected Genoese sailors subsequently sailed from Kaffa to Genoa, Messina, and Constantinople, introducing the Black Death into Europe. The story involving the catapult has been disputed. It is originally based on Gabriel de Mussis of Piacenza in Italy who wrote about the plague in 1348. It is more likely that rats carrying plague infested fleas went from camp to city and thereby infected the Genoese. In 1356 Jani Beg conducted a military campaign in Azerbaijan and conquered the city of Tabriz, installing his own governor. He also asserted Jochid dominance over the Chagatai Khanate, attempting to unite the three khanates of the Mongol Empire. After accepting surrender from Shaikh Uvais, Jani Beg boasted that three uluses (districts/nations) of the Mongol Empire were under his control. Soon after this, he faced an uprising in Tabriz resulting in the rise to power of the Jalayirid dynasty, an offshoot of Ilkhanate, and ultimately in the death of the Khan. Muscovy's Chudov Monastery, founded at about the time of Jani Beg's fall by Metropolitan Aleksii and Sergei of Radonezh, was built on land that according to legend was granted to Aleksii by the Khan as thanks for the miraculous curing of his mother Taydula by the former. The reign of Jani Beg was marked by the first signs of the feudal strife which would eventually contribute to the demise of the Golden Horde.