Modern Chinese and international research using new methods like drones systematically studies the Great wall of China. Its visibility from space is a legend, but its size actually ranks as world's largest monument. It never was a single wall, but a system of several segments, repeatedly altered over time, in successive attempts to prevent invasions from raider tribes, like the Xiongnu, adapted to the terrain, with an elaborate system of garrison towers, advanced tower posts and communication system. Building and manning it proved extremely costly. It failed to prevent the Mongol armies of Genghis Khan annexing China, his great successor Kublai Khan built a wall system to fit his larger empire. After the Ming dynasty finally expelled the Mongols, the 'primitive' walls were replaced by the final stone version, using a brick type solidified with rice starch. While the unprecedented mobilization of means for construction and garrisons crippled the treasury, it proved useless against the ... 你不知道的万里长城,由秋霞电影网收集来源于腾讯视频、爱奇艺、优酷网、以及m3u8在线资源等,本站除了提供热播的国产电视剧和韩国电视剧之外,还提供高清的电影,全部都免费播放,如果你没有找到想看的影视作品,可以给我们留言,让我们帮您寻找。最后秋霞电影网提醒您:注意保护自己的眼睛,播放你不知道的万里长城的同时,注意眼睛与手机/电脑的距离,不可离的太近,也不可长时间观看,注意适当的休息。