During his speech Tuesday night from campaign headquarters in Florida, Donald Trump invoked the Great Wall of China when justifying the feasibility of his plan to erect a wall along the

US-Mexico border.

“The Great Wall of China, built 2,000 years ago, is 13,000 miles long, folks,” the Republican presidential frontrunner said. “And they didn’t have ... tractors, they didn’t have cranes, they didn’t have excavation equipment.”

His remarks echoed comments made in August when he told Fox News anchor Bill O’Reilly that his proposed border wall would be “peanuts” compared with what the ancient Chinese accomplished.

While Trump’s departure from his usual loud complaints about China is welcome, Trump should keep in mind a few facts about the Great Wall the next time he draws the parallel.

Yes, Trump is technically right that the entire Great Wall of China spans about 21,000km: a landmark survey by Chinese authorities in 2012 found that its overlapping series of fortifications measured more than double previous estimates. But the Great Wall was built over an extended period in different phases and locations.

It also very long time to build.

The wall’s construction began more than 2,000 years ago during the Warring States period. The triumphant Qin dynasty embarked on the first ambitious wall project in the 3rd-century BC, attempting to erect a barrier against rival factions and marauding tribes that would stretch from the plateaus of the hinterland to the sea.

Over the centuries, successive dynasties would add and develop the fortifications, which crisscross a stunning diversity of terrain. The spectacular ruins now traversed by tourists are all largely the work of the Ming dynasty, which began its segments of the Great Wall in the 15th century after making Beijing its capital. The wall, ultimately, didn’t protect the dynasty, which was swept away by invading Manchu armies, which went on to set up the Qing dynasty.

Also, a lot of people died building it.

Sure, the Chinese did not have Caterpillar equipment or John Deere tractors, as Trump giddily exclaimed. But they did have a feudal system of enforced labour that enabled the wall’s construction. Some historical accounts estimate that as many as half a million workers perished building the fortification.

The wall didn’t quite do the job Trump thinks it did, either. For all its majesty, it was very porous. The Mongols, Manchus and others all breached this great defence and went on to establish their dominion behind its ramparts.