Did the Great Wall of China protect the Chinese from the Mongolians?

Not against the Mongolians per se – it protected them against their horses.

It bothered me for a really long time. As far as I could tell, you could simply scale the wall. There are places where it’s barely more than a few meters tall (sure, you have to climb a pretty steep hill first), but for a footman, it wouldn’t be a challenge at all.

The truth is though, what was dangerous wasn’t the Mongolians – it was Mongolians on horseback.

Dan Carlin does a fascinating job of explaining just how effective these forces were, and I definitely recommend you check out his Wrath of the Khans episodes. Essentially, hit and run tactics and a complete mastery of horseback riding, given that the Mongols essentially grew up on them, to an extent that they could shoot arrows incredibly precisely, mid gallop, while sliding down on one side of the horse for cover. Insane.

The speed that a horse-only army provided the Mongols was terrifying for China (and the world) – especially as they mostly relied on infantry troops.

Hence the solution of the wall – it wasn’t meant for the Mongols, it was meant to keep the horses out. Try getting a horse to climb up a steep hill, and then have to build an elaborate contraption to get them up the wall and down it again. By the time the Mongols were able to do that, China had time to bring in its massive infantry troops and stop them.

Except for this horse. This horse had no problems with the Great Wall of China.

The App That Wants to Simplify Postal Addresses

A British startup is assigning a unique name to every meter of Earth’s surface. Should addressing systems be universalized—and privatized?

.. Its address doesn’t just tell [you] where it is, but also what road to take to get to the front gate

.. What3Words envisions a universal addressing system, functional in any language, that refers to locations more precisely than street addresses can.

.. its leaders split Earth’s complete land and ocean surface area to 57 trillion three-by-three meter squares. Every individual grid square has a distinctive name, expressed as three words

.. there is no free or open database of how every What3Words address lines up with a GPS coordinate. In fact, charging for access to that database is exactly how the startup What3Words makes money.

.. Mongolia is the least densely populated sovereign nation on the planet.

.. “There’s really no addresses at all for most of the country,” Sheldrick told me.

.. What3Words will provide a national addressing system for Mongolia

.. In the early 2000s, the federal government and other organizations began using these IDs, called DUNS numbers, to organize companies that wanted to bid for contracts.

.. The U.S. government has paid Dun & Bradstreet millions to use the DUNS system.

 .. At first, mail was addressed to rural customers only by their name, city, and state. Local postmasters memorized the rest.

.. “It’s only within the last decade that every house has a street address,” says Nancy Pope, a historian at the Smithsonian National Postal Museum. “You end up with these street addresses that are in the tens of thousands, because they’re on a rural road tens of miles from the nearest town.”

.. What3Words addresses are designed to fail catastrophically, and therefore noticeably, Sheldrick told me. A single misplaced letter will never send a package 10 miles in the wrong direction, as a reversed digit in a latitude-longitude coordinate might. Instead, it will send it to another continent.

.. Once inside the ecosystem, its ownership could start extracting rents.

 .. But it doesn’t matter if users personally trust Sheldrick or the What3Words team. Intellectual property rights can easily change hands, and they always outlive their owners and their owners’ good intentions.


This means, for example, that a town is barred by law from releasing a dataset describing when garbage will get picked up where.

The British government is now spending £5 million to rebuild an open version of the exact same postcode registry that it sold off three years ago.