History of the Great Wall of China

No one can tell precisely when the building of the Great Wall was started but it is popularly believed that it originated as a military fortification against intrusion by tribes on the borders during the earlier Zhou Dynasty. Late in the Spring and Autumn Period (770 BC - 476 BC), the ducal states extended the defence work and built "great" structures to prevent the attacks from other states. It was not until the Qin Dynasty that the …

…this giant dragon. For centuries, the wall served succeeding dynasties as an efficient military defence. However, it was only when a dynasty had weakened from within that invaders from the north were able to advance and conquer. Both the Mongols (Yuan Dynasty, 1271-1368) and the Manchurians (Qing Dynasty, 1644-1911) were able take power because of weakness of the government and poverty of the people but never due to any possibility of weakness of the Wall.