The
Great Wall of China is a series of
fortifications made of stone, brick,
tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China to protect the
Chinese states and
empires against the raids and invasions of the various nomadic groups of the
Eurasian Steppe. Several walls were being built as early as the 7th century ; these, later joined together and made bigger and stronger, are now collectively referred to as the Great Wall. Especially famous is the wall built 220–206 by
Qin Shi Huang, the first Emperor of China. Little of that wall remains. Since then, the Great Wall has on and off been rebuilt, maintained, and enhanced; the majority of the existing wall is from the
Ming Dynasty.