Russian specific principalities
In Russian historiography the term Upper Oka Principalities () traditionally applies to about a dozen tiny and ephemeral polities situated along the upper course of the Oka River at the turn of the 14th and 15th centuries. They were reigned by the "upper princes", each of which descended from Mikhail Vsevolodovich of Chernigov (Grand Prince of Kiev c. 1236–1243). Nowadays, the areas concerned lie within the bounds of the Tula Oblast, Kaluga Oblast, Oryol Oblast and Bryansk Oblast of the Russian Federation.
Following the Mongol invasion of Kievan Rus' of 1223–1240, the formerly prominent Olgovichi clan of the Principality of Chernigov gradually declined to a point where the descendants of Mikhail of Chernigov (died 1246) ruled dozens of quasi-sovereign entities. As the principalities were wedged in between the ever-expanding Grand Duchy of Lithuania to the west and the nascent Principality of Moscow to the north, their rulers were constricted to continually fluctuate between these two major powers as buffer states.
By the end of the 14th century, they were obliged to pay annual tribute to Lithuania. The strengthening alliance of Lithuanian rulers with Roman Catholic Poland caused shifts in the balance of power in the region. Most Orthodox rulers of the Upper Oka Principalities, therefore, started to look to Moscow for protection against Lithuanian expansionism. Others sought Lithuanian protection against Muscovite aggression, such as Prince Ivan of Mozhaysk who in 1454 fled to Lithuania to escape from Vasily II of Moscow. Towards the end of the 15th century, most of these princelings had moved to the Muscovite court. In 1494 Lithuania finally renounced her claims to the region.
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