According to modern historians, the very first civilization on Earth arose in Mesopotamia, in the south of present-day Iraq, no earlier than 6000 BC. All subsequent human civilizations are known and studied to varying degrees. However, some scientific knowledge and technical achievements of representatives of these civilizations are far ahead of the level that would correspond to their natural development, and still remain inexplicable historical mysteries. Moreover, in the course of archaeological, anthropological and historical research, a lot of material evidence has been collected to suggest that that highly developed civilizations already existed on our planet tens and hundreds of thousands and even hundreds of millions of years ago.

This is about such historical mysteries, evidence and facts, about bold and sometimes extravagant hypotheses that reveal the secrets of origin, time and the place of existence of disappeared earthly civilizations, and is described in this book, designed for a wide range of inquisitive readers interested in the history of our planet.