Excitement abounds regarding the vicissitude of the Wall of the Qin, Han, and Ming Dynasties. The Great Wall was originally built in the Spring and Autumn, and Warring States Periods as a defensive fortification by the three states: Yan, Zhao and Qin. It went through constant extensions and repairs in later dynasties. It began as independent walls for different states when it was first built, and did not become the "Great" wall until the Qin Dynasty. Emperor Qin Shihuang succeeded in his effort to have the walls joined together to fend off the invasions from the Huns in the north. Since then, the Wall has served as a monument of the Chinese nation throughout history. Great Wall carries a considerable part of Chinese culture. It has long been incorporated into Chinese mythology and symbolism. The most well-known legend is about the collapse of a section of the Wall caused by Meng Jiangnu, who cried bitterly over the death of her husband after he died while building the wall. This legend has been spread widely through textbooks, folk songs and traditional operas. Following a 45-day long survey of 101 sections of the Wall in different provinces, the China Great Wall Academy reported on December 12, 2002 that the forces of nature and destruction by mankind are bringing about gradual reduction of extent of the Wall with the result that less than 30% remains in good condition. The Academy has called for greater protection of this important relic.