Historians were not able to study the past except thanks to what nations wrote about their conditions, meaning that history begins when man came to know the art of writing about four thousand years before Christ. Before the knowledge of writing, many nations lived on the surface of the Earth. There is no way to describe what they were except by studying their various effects, especially the various machines they used. Historians used to call the distant times in which these nations lived "prehistoric."
The "prehistoric" era is divided into four eras according to the tools used: The oldest of all is an era in which man made the tools he needed from stones, and this is called the "Paleolithic Age." Then, after that, man began to advance in stone carving, and the stone tools became amazingly perfect, and the era of their use is known as the "New Stone Age." After that, he learned to use metals, so he made tools from copper as he found it on the ground, and after that he was able to use iron, and that In the fourth era of prehistoric times.