When faced with a threat or simply with contact with what we learned in graduate school to call The Other, our natural instinct is to build a wall to keep Them out or to keep Us in. *

The earliest cities that we know of, the tel culture in what is now Palestine, were built on hills and surrounded by massive defensive walls built of rubble mortared together with mud. As cities grew, so did the walls. Sometimes they were built of mud brick, as in ancient Mesopotamia. Sometimes they were built of stone, as in pretty much anywhere in medieval Europe. They worked pretty well as an way to defend a city until the arrival of gunpowder from China changed the nature of siege warfare in the fifteenth century.

Walls on a grander scale have been less successful. Take, for instance, the grandest wall of all, the Great Wall of China.**

The simple version is that the wall was built, beginning around 220 BCE as a military defense system in northern China against inroads by horse-riding “barbarians” from the steppes.*** In fact, the wall was not a single wall. It was a series of fortifications and watch towers built over several centuries beginning around 220 BCE along a 13,000 mile border.*** * (More or less. The wall ruins haven’t been surveyed so we don’t actually know how long it was. And the border wasn’t a fixed point across the centuries.) Most of what we think of as the Great Wall of China was built during the Ming dynasty (1368-1644).

Moreover, wall-building wasn’t something that all members of the Chinese political classes agreed about, even in the Ming Dynasty. Building the wall was expensive in terms of both silver and lives. At any given point in Chinese history, there were men in power who believed that trade and peaceful coexistence with the nomads would be more effective than trying to keep them out. Folk songs lamenting the death of men forced into working on the wall suggests that peasants and urban laborers were even less enthusiastic. In short wall-building was a policy that people disagreed about.

The thing the wall did best was define who the barbarians were: civilized Han on one side of the wall and everyone else on the other side of the wall. But it didn’t keep the barbarians out. The Mongols and their predecessors continued to raid across the wall–and to ride through the long open stretches where no wall existed. More importantly, they also traded and intermarried with people on the Chinese side of the wall, who lived a long way from the places where people made the decision to keep the barbarians out. Mongols at the gates with horses to sell were doubtless more compelling that mandarins in Beijing with an axe to grind.

Prior to the rise of Communist China, when the wall became an official symbol of China’s greatness, Chinese historians described the wall as an example of what professor Arthur Waldron described as “a symbol of futility, waste, cruelty, bad policy.” Today the Great Wall of China is a UNESCO World Heritage site. It also draws thousands of tourists from across the world each year–so much for keeping the barbarians out.

*In the case of the Berlin Wall,the goal was to do both.

**The runner-up for the most famous wall in history, Hadrian’s wall, was roughly 68 miles in length. A toy wall by comparison. At least in length.

***Some of my favorite historical people

****No matter what you may read, you can’t see the Great Wall from the moon.