What is the Great Wall of China made out of?
The history of the construction of the Great Wall can be dated back to the Western Zhou Dynasty (11th century BC – 771 BC). But the wall at that time was only a line of fortresses standing to defend against attacks from the Yanyun (an ancient nomadic tribe in north China). The Period of the Warring States (476 BC – 221 BC) was an era when the seven states (Qi, Chu, Yan, Han, Zhao, Wei, Qin) were busy engaging in wall-construction for self-defense. Instead of one line, their walls stretched in the four directions and varied in length from several hundred miles to one or two thousand miles. In the Qin Dynasty (221 – 206 BC) the emperor Qin Shihuang ordered his laborers to connect these scattered walls and create some new sections, thus forming a Great Wall in northern and central China in the true sense. The Ming Dynasty (1368 – 1644) further developed the defensive system of the wall and strengthened it on a larger scale. It pushed the wall construction to its highest peak. The winding
