Alexander Vygantas was the duke of which city in Lithuania?
Vygantas Vygantas (baptized Alexander; Polish: "Wigunt" ; died June 28, 1392) was Duke of Kernavė. He was one of the sons of Algirdas, Grand Duke of Lithuania (1345–1377), and his second wife Uliana Alexandrovna of Tver.
Tautvilas Tautvilas (or Tautvila; died 1263) was Duke of Polatsk and one of the sons of Dausprungas and nephews of King of Lithuania Mindaugas. Tautvilas together with his brother Edivydas and uncle Vykintas waged a civil war against Mindaugas. The war resulted in coronation of Mindaugas.