The book offered to the attention of readers does not fit into any of the genres accepted in modern scientific literature. It cannot be called a popular science essay in the full sense of the word, despite the fact that it is written in a popular form and is intended for a wide range of readers. It popularizes, however, not the results of purely scientific, academic research written for a narrow circle of specialists, but a completely new study that is contained in it <...> ... the popular form, and most importantly, the author’s research method is fundamentally different from the form and method of monographs . L. N. Gumilev’s book can most likely be called a scientific treatise in the medieval sense of the word. Can such a long-out-of-use genre be considered suitable for modern scientific research? The answer to this question is given by the book itself.