Principality of Polotsk
Principality of Polotsk repeatedly asserted its sovereignty in relation to the other centers of Rus', becoming a political capital, the episcopal see of a bishopric and the controller of vassal territories among Balts in the west. The city's Cathedral of the Holy Wisdom (1044–66), though completely rebuilt over the years, remains a symbol of this independent-mindedness, rivaling churches of the same name in Novgorod and Kiev, referring to the original Hagia Sophia in Constantinople (and hence to claims of imperial prestige, authority and sovereignty). Cultural achievements of the Polatsk period include the work of the nun Euphrosyne of Polatsk (1120–1173), who built monasteries, transcribed books, promoted literacy and sponsored art (including local artisan Lazarus Bohsha's famous "Cross of Euphrosyne", a national symbol and treasure stolen during World War II), and the prolific, original Church Slavonic sermons and writings of Bishop Cyril of Turau (1130–1182).