salt among others were of great economic importance to the Novgorodians, who fought a protracted series of wars with Moscow beginning in the late 14th century in order to keep these lands. Losing them meant economic and cultural decline for the city and its inhabitants. Indeed, the ultimate failure of the Novgorodians to win these wars led to the downfall of the Novgorod Republic. Fall of the Republic Tver, Muscovy, and Lithuania fought over control of Novgorod and its enormous wealth from the 14th century. Upon becoming the Grand Prince of Vladimir, Mikhail Yaroslavich of Tver sent his governors to Novgorod. A series of disagreements with Mikhail pushed Novgorod towards closer ties with Muscovy during the reign of Grand Prince George. In part, Tver's proximity (the Tver Principality is contiguous with the Novgorodian Land) threatened Novgorod. It was feared that a Tverite prince would annex Novgorodian lands and thus weaken the Republic. At the time, though, Muscovy did not border Novgorod, and since the Muscovite princes were further afield, they were more acceptable as princes of Novgorod. They could come to Novgorod's aid when needed but would be too far away to meddle too much in the Republic's affairs. As Muscovy grew in strength, however, the Muscovite princes became a serious threat to Novgorod. Ivan Kalita, Simeon the Proud and other Muscovite monarchs sought to limit Novgorod's independence. In 1397, a critical conflict took place between Muscovy and Novgorod, when Moscow annexed the Dvina Lands along the course of the Northern Dvina. These lands were crucial to Novgorod's well-being since much of the city's furs came from there.Paul, "Secular Power and the Archbishops of Novgorod Before the Muscovite Conquest," 258–259. This territory was returned to Novgorod the following year. Resisting the Muscovite oppression, the government of Novgorod sought an alliance with Poland–Lithuania. Most Novgorodian boyars wished to maintain the Republic's independence since if Novgorod were to be conquered, the boyars' wealth would flow to the grand prince and his Muscovite boyars, and the Novgorodians would fall into decline. Most of them didn't earn enough to pay for war. According to tradition, Marfa Boretskaya, the wife of Posadnik Isak Boretskii, was the main proponent of an alliance with Poland-Lithuania to save the Republic. According to this legend, Boretskaya invited the Lithuanian princeling Mikhail Olelkovich and asked him to become her husband and the ruler of Novgorod. She also concluded an alliance