Historians have urged more efforts to protect the western sections of the Great Wall in the wake of an official survey of the historic structure. Between July 6 and 12, the National Committee of the Chinese People\'s Political Consultative Conference, the country\'s top political advisory body, arranged for experts to check up on the state of the Wall in Gansu province, which holds an estimated 3,600 km of its total 21,196.18 km. The team visited 10 major sites in five cities, including Dingxi, Wuwei, Zhangye, Jiayuguan and Jiuquan. They were alarmed at the condition of the Wall, built in the dynasties of Qin (221B.C.--206 B.C.), Han (202B.C.--220A.D.) and Ming (1368A.D.--1644A.D.). Unlike eastern parts of the Great Wall in Beijing, Heibei and Liaoning, which were mostly constructed with stones and bricks, the sections in Gansu were built with tamped earth. After centuries of erosion from fierce wind and frequent sandstorms, they have become extremely fragile. In Weiyuan County, some parts built in the Warring States Period (475 B.C.--221 B.C.) have been merged with surrounding cropland, while another 200-km-long section built in the Ming Dynasty in Dingxi city has suffered weathering, collapse and biological damage over a long period. \"The Great Wall in Gansu is facing both natural and human damage,\" said Yang Huifu, head of the Gansu Bureau of Cultural Relics, adding that some walls have been swept away by torrential rain and heavy wind. Yang said that in recent years, authorities have limited damage from humans, but that such problems remained in some areas. The reseach group believe that, while western sections of the Wall are less attractive to tourists, the structure and the cultural relics that continue to be unearthed alongside it must be preserved as crucial materials for China\'s historical, geographical, political, martial and cultural research. Besides the disadvantages of geography and weather, other problems the experts encountered with the preservation of the western Wall include a lack of research personnnel and protective technology, according to Duan Qingbo, a senior researcher with Northwest University in Shaanxi province. Duan said that the dozen researchers from Dunhuang Academy tasked with taking care of the remaining sections scattered in the province are not enough. Meanwhile, the experts suggested that awareness must be raised among local residents, as well as tourism operators, of the need to protect cultural relics. \"The protection of the ancient Great Wall sections in western China is a hard nut to crack,\" Duan said, adding that new systems and all-around efforts from society are needed if it is to be succesful. Construction of the Great Wall, listed as a world cultural heritage by UNESCO in 1987, began during the reign of China\'s first emperor, Qin Shihuang (259-210 B.C.), to keep out foreign invaders. [ It passes through 10 provinces, municipalities and autonomous regions in northern China, including Liaoning, Hebei, Tianjin, Beijing, Shanxi, Inner Mongolia, Shaanxi, Ningxia, Gansu and Qinghai.