The invasion of the Mongol-Tatar hordes of Batu in the fall and winter of 1237-38 is the most muddy and controversial page in Russian history. The official version does not stand up to criticism, there are countless questions! It is not surprising that the school teacher agreed to the offer to personally be in the thick of things and see everything with his own eyes. I thought it was a joke, but no! Once, and he is already in the thirteenth century, and with the opportunity to return everything is not at all easy. And is it necessary to go back, when here and now it is possible to correct so many troubles and direct the history of Russia along a new, yet unexplored path?!