Great Russian War

The Great Russian War was a conflict taking place during Episode VI of Varna, which resulted in the collapse of the Golden Horde.
The conflict began with the secession of the Sibir Khanate from the Horde in late 1474, which prompted the Lithuanians to begin an invasion, with backing from their Polish overlord. Hungary was also in a personal union with Poland, so they also sent support. In 1475, the Triarchy was backed by the Russian states of Muscovy, Ryazan and Pskov, who all rebelled against their Mongol oppressor, as well as the Kingdom of Theodoro in Crimea.
Lithuania began their advancements on the south bank of the Dnipro river, with Theodoran aid, before they were joined by the Poles and Ryazanis in capturing all territory west of the Don river, as Muscovy sent their troops as far east as the Volga, before moving south to meet the allies near Sarai, the Horde's capital. At the same time, the Kazan Khanate seized some of the Golden Horde's northern territories, as eastern Crimea was captured and annexed by Venice. In April 1476, two uprisings began in Circassia and the city of Astrakhan, against the Mongols.
As the allies closed in on Sarai and besieged the city, the Horde was invaded by several other states in 1477; namely the Nogai Horde, the Oirat Confederation, and Transoxiana; who had all taken a page out of Kazan's book. As well as this, three khanates broke out of the Horde; those being the Uzbek Khanate, Chuvash, and Cuman-Kipchak. By the end of the year, Sarai fell, and the Horde collapsed. A new government would go on to form the Great Horde, and the war would be ended by the Treaty of Azov.