The Great Wall of China is a series of fortifications built along the historical northern borders of China to protect the Chinese Empire from nomadic groups and military incursions. It is the longest wall in the world, stretching over 5,500 miles from the east coast of China to the Gobi
From Wikipedia
The Great Wall of China is a series of fortifications in China. They were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic groups from the Eurasian Steppe. The first walls date to the 7th century BC; these were joined together in the Qin dynasty. Successive dynasties expanded the wall system; the best-known sections were built by the Ming dynasty (1368–1644).