Principality of Chernigov
Following the Mongol invasion of Russia of 1223-1240, the formerly mighty Principality of Chernigov gradually degenerated to a point where the descendants of Mikhail of Chernigov (c. 1185 – 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 Grand Duchy of Muscovy to the north, their rulers were constricted to continually fluctuate between these two major powers as buffer states.