Principality of Polotsk
The Principality of Polotsk escaped the Mongol invasion of Rus' in 1237–1239. However, pagan Lithuanians began consolidating lands of the principality, and in 1240 Polotsk became a part of the Grand Duchy of Lithuania. It officially became part of Lithuania in 1307, though it retained some degree of local autonomy until the 1390s. Then the principality was abolished and became part of the Połock Voivodeship.