Answer:
The wall was built to help keep out northern invaders like the Mongols. Smaller walls had been built over the years, but the first Emperor of China, Qin Shi Huang, decided that he wanted a single giant wall to protect his northern borders. Also did you know? When Emperor Qin Shi Huang ordered construction of the Great Wall around 221 B.C., the labor force that built the wall was made up largely of soldiers and convicts. It is said that as many as 400,000 people died during the wall's construction; many of these workers were buried within the wall itself