Now, having determined all the sources of the Gustynja Chronicle for the 14th century, and knowing the techniques accepted by the author for their processing, we can very easily explain the origin of the news about the "Kyiv prince Theodor".
How did this text come about? I imagine the course of the author’s reasoning as follows […]
Thus, one can not doubt that the records of the Gustynja Chronicle for the years 1361 to 1362 are the next (the 9th by my count) unsuccessful attempt of a combination of sources known to the author GL and to us – the Nikon Chronicle, the "Lithuanian" Chronicle (presumably Lit5L) and the work of A. Gwagnini. They do not have source value.
Despite the simplicity of this conclusion, the combination of the author GL was a huge success in historiography, supported – contrary to evidence! – by subsequent historians until our time, that is, until July 23, 2018 inclusive. And meanwhile:
1, there had not been any "battle on the Blue Water" Algirdas with the Tatars.
2, the specific time and circumstances of the transition of Podillia and Kyiv under the authority of Lithuania remain unknown.
3, the specific time and circumstances of the departure of the "Kyiv prince" Theodor from power remain unknown.
4, the specific time and circumstances of the installing of Vladimir Olgerdovich in Kyiv remain unknown.