The Great Wall was made by the Qin and Han dynasty's to keep out invaders and other enemies. The benefits did outweigh the cost because it kept your city protected, it was harder for invaders to attack.They also put troops in the frontier areas of the Wall to increase the security level.According to document A it states that "the government will construct walled cities, well protected by high walls, deep moats, catapults, and thorns." This shows that the Qin and Han wanted to make it harder for the mongols to attack and that china wanted to be prepared for when other dangerous situations happen.Another thing the Qin and Han dynasties made was to impress