The great wall of china was built as a means of protection and detection. The chinese emperor wanted to protect his lands from the invading northern mongolians and huns. The wall provided a difficult barrier to overcome for china’s enemies, as well as providing a speedy means of communicating. From the watch towers that were strategically located at intervals running throughout the wall, spotting an invading enemy could be done even when they were far off. After the enemy was spotted, the watch tower would give off a signal to the nearest watchtower and the signalling would continue all the way down the wall until it reached the capital. Thus, the emperor would be alerted of the eminent attack by the time the attackers reached the wall. Basically, the wall serves as defensive fortification.
The Great Wall served 2 purposes – to defend against major military invasions by the Mongols, but more importantly to defend against Mongolian raiding parties where the Mongols would penetrate the border with a fast-moving small army (usually cavalry), raid a village/town in inland China & go back across the border before the Chinese troops could pursue them. Because China’s border was stretched over thousands of kilometers, the only effective way to prevent these raiding parties was to build the wall (the alternative would’ve been to have hundreds of of thousands of soldiers on patrol over the 6,700 kilometers of border).
Several walls, referred to as the Great Wall of China, were built since the 5th century BC. The most famous is the wall built between 220 BC and 200 BC by the first Emperor of China, Qin Shi Huang; little of it remains. It was much farther north than the current wall, which was built during the Ming Dynasty.[ Most of the ancient walls have eroded away over the centuries, and very few sections remain today. Possibly as many as one million people died building the Wall under the Qin Dynasty. Later, the Han, Sui, Northern and Jin dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders. At its peak, the Ming Wall was guarded by more than one million men. The Manchus were finally able to cross the Great Wall in 1644, when the gates at Shanhaiguan were opened by Wu Sangui, a Ming border general who disliked the activities of rulers of the Shun Dynasty.
They built it to keep invaders out. It was a very amazing civilization but a lot of people died building it, and it took a very long time. also back then just like the Egyptian Civilization, and the Summarians before that, focused their lives on major projects like that, to work together and have something to be proud of and to look forward to instead of building weapons that would kill people and have money rule their lives.