The civilization was the Chinese. <span />
The Stone Age<span> was a time thousands of years ago, when humans lived in caves and jungles. </span>Life<span> was simple, and there were only two main things to do – to protect themselves from the wild animals and to gather food. It started almost with the evolution of mankind. For both purposes, people made tools from </span>stone<span>.</span>
So they can be made for less money than conventional buildings.
