Great Wall of China

The Great Wall of China is not one wall but a long sequence of ramparts, trenches, watchtowers and forts built over some two thousand years along the northern edge of the Chinese world, where farmland gives way to the Mongolian steppe. Rival states began walling their borders in the seventh century BCE, the first emperor joined many of these lines together, and later dynasties rebuilt and extended them, above all the Ming. A national survey completed in 2012 counted more than 21,000 kilometres of walls and trenches of all periods, about half of them in Inner Mongolia and Hebei.

Chinese poetry from around the seventh century BCE already mentions a fortification against northern raiders. As central Zhou authority collapsed, states such as Chu, Qi, Zhao, Yan and Qin built their own walls, usually of earth and gravel pounded between wooden boards; the Qi wall, begun in 441 BCE, is the oldest that still survives. When Qin conquered its rivals in 221 BCE, its ruler, Qin Shi Huang, pulled down the internal walls that divided the old states but had his general Meng Tian link the northern ones into a single frontier against the Xiongnu. Little of this Qin work survives, and its exact course is unknown.

The Han dynasty, especially under Emperor Wu (r. 141–87 BCE), pushed the defences far to the west as far as the Yumen Pass in what is now Gansu. Later states repaired or replaced the walls according to their own needs, including the Northern Wei, Northern Qi and Sui, as well as dynasties of steppe or forest origin such as the Khitan Liao, the Tangut Western Xia and the Jurchen Jin. The Tang and Song did little in the north. The walls did not stop the Mongols, who in 1211 simply rode around the Jin fortifications; under the Mongol Yuan dynasty the frontier lay deep inside a single empire.

The stone and brick wall that most visitors know is largely the work of the Ming dynasty, which drove out the Yuan in 1368. After the Tumu Crisis of 1449, when the Mongols destroyed a Ming army and captured the emperor, the court turned to building continuous fortified lines. Walls went up across the Ordos in the 1470s, the defences guarding Beijing were doubled in the 1540s, and in the late 1560s and early 1570s the generals Qi Jiguang and Tan Lun had about 1,200 brick watchtowers built in the capital region. Bricks and lime mortar made these sections far stronger than the earlier rammed earth. The 2012 survey measured the Ming system at about 8,850 kilometres, including natural barriers.

The wall failed at the decisive moment. In 1644 the rebel Li Zicheng took Beijing, and Wu Sangui, the Ming commander at Shanhai Pass where the wall meets the sea, opened its gates to the Manchus, who seized the capital and founded the Qing dynasty. With Mongolia and Manchuria inside the Qing empire, the wall lost its defensive purpose, though parts of it were used to restrict Han Chinese migration into Manchuria.

European descriptions began to circulate in the sixteenth century, and later writers wrongly treated the Ming wall as the original built by the first emperor. After the Opium Wars of the nineteenth century it became a goal for foreign visitors. In the twentieth century it turned into a national emblem: Chinese troops fought behind it against Japan in 1933, and a 1934 poem about it supplied words for the song later adopted as the national anthem of the People's Republic. The Badaling section near Beijing was restored and opened in the late 1950s, yet during the Cultural Revolution (1966–1976) Red Guards deliberately demolished hundreds of kilometres and reused the stone.

In the 1980s Deng Xiaoping launched a campaign to restore the wall, and UNESCO listed it as a World Heritage site in 1987. China passed specific laws to protect it from 2003. Problems remain. A 2012 official report found that about 22 per cent of the Ming wall had disappeared, desert sections in Gansu are being worn away by sandstorms, villagers have long taken its stones for building, and poor restorations, such as a stretch covered in concrete in 2014, have drawn criticism. Busy sections near Beijing now limit daily visitor numbers.