Why was the Great Wall of China built?

The Great Wall of China is the collective name of a series of fortification systems generally built across the historical northern borders of China to protect and consolidate territories of Chinese states and empires against various nomadic groups of the steppe and their polities.

Several walls were being built from as early as the 7th century BC by ancient Chinese states; selective stretches were later joined together by Qin Shi Huang (220–206 BC), the first Emperor of China. Little of the Qin wall remains.

Later on, many successive dynasties have built and maintained multiple stretches of border walls. The most well-known sections of the wall were built by the Ming dynasty (1368–1644).