After his father
Öz Beg died in 1341, Jani Beg's older brother and rival
Tini Beg was in the east, possibly preparing for an attack. As soon as Tini Beg entered the central lands, he was killed by the followers of Jani Beg. Khiḍr Beg, a younger brother, was also killed on his orders. Jani Beg was elected as khan in 1342 by the
kurultai with the support of his mother
Taydula Khatun. Jani Beg is known to have actively interfered in the affairs of the
Russian principalities and
Lithuania. Like his father, Jani Beg supported the house of
Moscow and its heads,
Simeon and
Ivan II. Relations between the Russian principalities were generally peaceful, with Jani Beg only permitting one small-scale operation against
Ryazan; however, he interfered in Moscow's relations with
Suzdal, supported anti-Muscovite elements in Ryazan, and contributed to
Tver's fragmentation. He also allowed those principalities to grow increasingly independent, to the point that their rulers began calling themselves grand princes – a title that had been reserved to only the ruler of
Vladimir. The Russian chroniclers referred to him as "the good tsar". Jani Beg also confirmed the
yarlik to the
Venetians at the start of his reign. However, in September 1343, a Venetian noble named Andreolo Civran killed a Mongol official in
Tanais, which led to Jani Beg expelling all the
Latins from the Italian colonies. The Venetian senate condemned Civran and sent envoys to negotiate with Jani Beg, but Jani Beg demanded that Civran be judged by a Mongol court. The
Genoese and Venetians formed a temporary alliance and imposed a trade embargo, while Jani Beg responded by sending more troops to
Kaffa in Crimea. Jani Beg commanded a massive Crimean
Tatar force that attacked Kaffa, then a Genoese colony. 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
plague among his troops. Jani Beg's army catapulted infected corpses into Kaffa in an attempt to use the plague 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 the Jani Beg's camp to the city and thereby infected the Genoese. In 1342, Janibeg temporarily imposed a tax on the
Russian Church at the instigation of a Russian prince who harbored resentment toward the church due to its significant wealth and reputation. By that time, the Golden Horde's treasury had drained because of natural disasters and warfare; however, Janibeg restored the tax exempt status of the church in September 1347 and reconfirmed it in 1351, returning to the religious policy of Genghis Khan. Despite the incident, Jani Beg continued to protect the Russian Church. Following the death of Simeon of Moscow in 1353, Jani Beg sided with Simeon's younger brother, Ivan II, when the throne of Vladimir was contested by the prince of Nizhny Novgorod-Suzdal. As a result, Jani Beg managed to maintain the balance of power among the principalities and prevent war from breaking out over the succession. The princes of Moscow were considered loyal and Jani Beg viewed Moscow as the best counterbalance to the growing power of Lithuania. In the winter of 1356–1357, Jani Beg attacked the region of
Azerbaijan in Iran and conquered the city of
Tabriz, installing his own governor. The
Ilkhanate was politically fragmented and the region was under the control of
Malek Ashraf, but Jani Beg was able to secure the support of the
Shirvanshah, and his army of 300,000 was able to easily take the region. To celebrate his victory, Jani Beg had coins minted in the city. He also asserted Jochid dominance over the
Chagatai Khanate, but as soon as the Jochid armies left, the governor of Tabriz declared independence and was soon killed by the
Muzaffarid ruler
Mubariz al-Din Muhammad, who then withdrew from the region as he could not hold it. This resulted in the
Jalayirids annexing the region. Following his conquests, Berdi Beg returned to Sarai in 1357, but on the way, he fell ill and died. Persian sources say either
Berdi Beg or the
beys were responsible for his death due to Jani Beg being too old, while the
Nikon Chronicle, a later Russian source, says that the beys strangled him to death. Jani Beg's contemporaries suspected that he was killed on the order of Berdi Beg, but the exact cause of death is unknown due to the lack of direct sources. ==Legacy==