Great Wall of China the optics much better, rendering photographic evidence irrelevant to the issue of whether it is visible to the naked eye. Great Wall of China 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 with an eye to expansion. Several walls were being built as early as the 7th century BC; these, later joined together and
Great Wall of China undertake any significant effort in the region. The Liao, Jin, and Yuan dynasties, who ruled Northern China throughout most of the 10th–13th centuries, constructed defensive walls in the 12th century but those were located much to the north of the Great Wall as we know it, within China's province of Inner Mongolia and in Mongolia itself. The Great Wall concept was revived again under the Ming in the 14th century, and following the Ming army's defeat by the Oirats in the Battle of Tumu. The Ming had failed to gain a clear upper hand over the Mongolian tribes after successive