“Tver Baskak” is a science-fiction novel by Dmitry Emelyanov, the first book of the eponymous cycle, genres: historical science fiction and accidentals (isekai). The invasion of the Mongol-Tatar hordes of Batu in the autumn-winter of 1237–38 is the murkiest and most controversial page in Russian history. The official version can’t withstand any criticism—questions are countless! No wonder a school teacher agreed to take up the offer to personally be in the thick of events and see everything firsthand. He thought it was a joke—no! And suddenly he’s already in the thirteenth century, and the possibility to return is much less simple. And does he even need to go back, when here and now he can fix so many troubles and steer the history of Russia along a new path that has never been explored before?!