The book “The Unknown Mao” by John Halliday and Yong Zhang became one of the world's bestsellers. It is unprecedented both in the volume of sources used and in the number of historical discoveries. The documentary basis was made up of materials from the archives of Taiwan, the USA, Japan, Russia and a number of other countries. The authors managed to gain access to the archives of the People's Republic of China, despite the fact that official Beijing did not welcome the creation of an uncensored biography of Mao. The book, requested in China, revealed to the world community the personal phenomenon of the communist tyrant.