[1] Most likely he was the son of Butvydas, and a younger brother of Gediminas, the grand duke of Lithuania, his pagan name is unknown and he was baptized as Orthodox Fiodor.
The Lithuanian Chronicles mention that Gediminas installed his deputy Algimantas, son of Mindaugas from Olshanski family.
[7] The presence of a Tatar official led historians to believe that while Kiev was ruled by a Lithuanian, it had to pay a tribute to the Golden Horde.
[7] For a long time scholars assumed that Fiodor was of Rurikid origin (descendant of Oleg I of Chernigov) because of his Christian name.
However, in 1916, Russian historian Mikhail Priselkov published a list of property belonging to Theognostus, the metropolitan of Moscow.