This book is a sequel (or better: a prequel) to Immanuel Velikovsky's main work, the best-selling Worlds in Collision, in which he gave a detailed reconstruction of two global natural catastrophes based on information handed down by our ancestors. He mentioned there that, as part of his intensive research, he found numerous indications of even more catastrophes that took place earlier in the history of mankind. In the present book, the material collected by Velikovksy about this topic is presented to the public for the first time. His findings show just how turbulent the history of Earth and our planetary system was during the time of mankind and how little we actually know of all that today.