Would the Ming emperor’s foes have agreed to bankroll his Great Wall?

Zhang laughs. “[They] wouldn’t have done so.”

Across China, from the wall’s spectacular, cliff-hugging ruins near Beijing to its wind-battered remains here in the barren northwestern province of Gansu, scholars and enthusiasts have been pondering Trump’s pledge – repeated last month during the president’s address to congress – to build a “great, great wall” of his own.

What, if anything, do the two projects have in common? What might the designers of Trump’s barrier along the US-Mexico border glean from studying the history of China’s changcheng (“long wall”)? What challenges might the president face and what pitfalls might he avoid as he erects his own version of what one 19th-century adventurer called China’s “fantastic serpent of stone”?

Zhang, a 45-year-old history fanatic who has been visiting the wall since he was a year old, when his father was posted to a steel mill near Jiayuguan, says he sees striking parallels between the initiatives.

One targeted unruly nomads and the other Latin American migrants but ultimately both were designed to “protect people from outsiders”, he says.

That being so, Zhang says, there are several design elements Trump might borrow from his Chinese precursors, foremost among them the gaping ditches soldiers carved into the arid soil around the Jiayu Pass, a fortress built on the orders of the Hongwu emperor in 1372.

“If Trump builds this wall, it would be best for him to dig moats and to fill them with water as well,” Zhang suggests. “That would be my advice.”

China’s legendary fortification was not created as a single wall but as a network of at least 16 distinct and unconnected barriers built over the course of more than 2,400 years to subdue unwanted outsiders. Scholars say that, by describing his frontier project as a “great wall”, the president is evoking not a marvel of engineering but a calamitous and ill-conceived folly.

“When Trump said, ‘I’m going to build a great wall,’ I thought, ‘What the hell are you talking about? You’re going to have stonemasons down there?’ I mean, it’s ridiculous,” says Arthur Waldron, a University of Pennsylvania professor who wrote one of the most detailed studies of China’s wall.

“The purpose [of China’s wall] was to keep out tens of thousands of guys on horseback who could ride faster than anybody, who could shoot arrows more accurately than anybody, who didn’t give a whit for all of China’s great civilisation but were very happy to get grain, metals, silks and beautiful Chinese princesses and so forth and take them back out into the steppe,” says Waldron, the author of The Great Wall of China: From History to Myth (1990).

But in practice, Waldron says, the wall proved a catastrophic and costly failure that drained the Ming’s coffers and ultimately failed to prevent its downfall when the Manchus stormed China and established the Qing dynasty, in 1644.

“This wall was the product of imperial oppression, it cost the lives of many innocent people and also it didn’t work,” says Waldron.

He said Trump is right to claim immigration policy has become “very, very lax” and argues some action is necessary. But naming his barrier after a structure synonymous with xenophobia and isolation is a “terrible mistake” for “an extraordinary immigrant nation”.

In China, where the Communist Party has transformed the landmark into a potent symbol of the country’s revival, Trump’s project has found a more sympathetic audience.

“I think it is a good thing for the Americans,” enthuses Zhang, who credits China’s Unesco World Heritage site with bringing peace and stability to sparsely populated strategic border regions such as the Hexi corridor, where the Jiayu Pass was built by the Ming.

Dong Yaohui, one of the founders of China’s Great Wall Society, says the meandering fortification has been an effective means of protecting residents of the empire’s often lawless fringes. Given the exorbitant cost of permanently stationing troops in such villages, how else would the central government have protected farmers whose harvests were pilfered by Mongol raiders?

Dong concedes many lives were lost building a structure some called the longest cemetery on Earth – “but the cost would have been much higher had there been no such thing as the Great Wall”.

Zhang, whose museum sits at the foot of the Jiayu Pass, flanked by snow-capped mountains and rock-strewn deserts, has little time for Great Wall detractors. A sign at the entrance to its permanent exhibition reads: “The Great Wall was a military system of defence of great magnificence … It is one of the greatest cultural and architectural miracles in the history of world civilisation.”

Zhang claims the Ming wall allowed foreign traders, diplomats and officials to safely come and go along the Silk Road while saving farmers from roaming bands of tribesmen who used “guerrilla tactics” to loot their properties.

Dong, however, acknowledges the structure’s history also holds some cautionary tales for Trump, perhaps none more urgent than that of the Jiajing emperor, who ruled from 1522 to 1567 and was known for his inflexible policies towards the steppe. Jiajing – who was notorious, according to Waldron’s research, for his deep hatred of nomads and lack of understanding of border matters – forbade all trade with outsiders and cut off their access to essential goods such as grain.

The result, notes Dong, was an almost constant state of war.

“Trump should understand [the story of Jiajing] when building the wall, and not focus solely on America’s interests,” he warns, arguing that flexible, semi-porous barriers are preferable to closed-off frontiers that often stoked hostilities.

“Strategic moves such as the Great Wall should be regarded as a means to maintain a balance … and certainly not a way to strangle one’s opponent to death through force,” he says. “It’s like when you are driving a car – it is good to transport people or goods but it is bad to simply run people over.”

Since taking office Trump has vowed to pursue the “immediate construction” of his border wall, despite suspicions that bureaucratic, budgetary and logistical hurdles mean he will end up with little more than a few hundred miles of fence.

“We will soon begin the construction of a great, great wall along our southern border,” he told Congress on February 28. “It will be started ahead of schedule and, when finished, it will be a very effective weapon against drugs and crime.”

Zhang says he has mixed feelings over Trump’s pharaonic scheme and suggests he might be better off using US tax dollars to boost Mexico’s economy. “Once the quality of life has improved [there], less people will want to go to the US illegally.”

Dong is also torn. “There are two possible results from Trump building this wall: one is that it might help him to obtain his goal of maintaining order between the US and Mexico; the other is that it might fuel conflicts – just as happened in the case of the Ming dynasty.”

Additional reporting by Wang Zhen

Guardian News & Media