Qin Wall was built to serve as a defence system in the northern part of the empire. As it followed the ridges of steep mountains or sides of deep gorges, it served well as a mighty barrier to prevent the cavalry attack of Xiongnu. Passes, barriers and beacon towers were added to reinforce the defensive effect. In this period, the Wall was made of layers of compacted earth. The section remaining at Linzhao in today's Gansu Province is a typical example. From the exposed transverse section, scientists have found that the foundation comprises a layer of raw earth, over 1.5 meters thick at the bottom, with further loess above, some three meters thick. The wall was built on this foundation from layers of tamped-earth. The tamped-earth process began with a simple wooden frame. Workers filled the frame with loose earth, which was then tamped into a compact layer 4 inches thick. The process was repeated layer upon layer, and the wall slowly rose four inches at a time. So you can imagine how long it will take to build a seven-meter high wall. Detritus was mixed into the wall to make it more solid.

The Great Wall of China is often thought to have been built by order of Qin Shihuang, the First Emperor of the Qin Dynasty (221-207 BC). It is true that as a national defence work, the Great Wall first took shape after the unification of China during that period. However, the construction of the separate sections started long before the Qin Dynasty. As early as the Spring and Autumn period (770-476 BC) and the period of the Warring States (475-221 BC), some sections of the walls were built by the seven powerful ducal states, the Qin, Qi, Chu, Han, Zhao, Wei and Yan for protection against each other. Also, some sections were built along the northern borders by the Qin, Zhao and Yan to fend off the Huns, who assaulted China constantly. These walls formed the origins of the Great Wall. When he established the Qin Dynasty, Emperor Qin Shihuang made every effort to protect the new Empire. He gave the order to build the Great Wall. This project involved joining the separate walls previously constructed plus a further extension of totally over 5000 kilometers cutting right across northern China, starting from Inner Mongolia in the east.

Emperor Qin Shihuang's contribution to the design of the Wall is considered to be of great importance as it ensured peace for the people in the northern part of China against the Huns and established a pattern of defence for future generations.

The Great Wall of the Qin Dynasty was divided into 3 sections: the eastern section, the middle section, and the western section. The eastern section, mostly built on the original wall of Yan State, started from Huade County, Inner Mongolia and ran into Fuxin City, Liaoning Province through Hebei Province. The middle section with beacon towers, mostly built by the Qin Dynasty, rose from Xinghe County, Inner Mongolia in the east and reached the desert to form a further protection system. The western section went along the Yellow River. It began in Min County, Gansu Province and wound its way to Yuzhong. Within this section, some parts were based on the walls of the Warring States Period.

The Great Wall of the Qin Dynasty was built at the expense of many lives. It involved the backbreaking toil of tens of thousands of people including conscripted soldiers, slaves, convicts as well as ordinary people. It is for this reason that the story of the Great Wall is often associated with the tyranny of the First Emperor of Qin.