The Han Dynasty's Great Wall | Ancient China from Above

[Suspenseful magical music] [Dramatic music] I'm now more than 230 miles west of the fortress of Jiayuguan. I'm here in the Kumtag Desert. It's one of the harshest environments I've ever been in in my life. Very little grows here. The temperatures are literally below freezing. It's a hell of a place to imagine finding archaeology.

Sarah's guiding me to faint traces of what looks like an even older wall that she spotted on the satellite data. [Epic adventurous music] If I get up here, I think I can get my first glimpse. Wow, this is cool. And it's not exactly what I expected. And it looks kind of primitive. I want to see more. I want to get up closer.

Here, in the middle of nowhere, a stretch of ancient wall. And it looks very different from anything I've seen so far. This is a very distinctive kind of material. We have rammed earth, packed down, with a reed foundation. These are reeds. This is actually a type of thick grass pressed in there to serve as a foundation to hold the wall stable. This framework is an ingenious way of building even with the desert's loose sand and gravel.

But if the Ming didn't build this, then who did? To find out, I'm meeting Jang Joon Min, the head of a team from the Gansu Institute of Relics and Archaeology, who are digging for answers. Wow, this is so cool. Tell me what you have here.

[Non-English speech]
TRANSLATOR: These are two arrowheads we found nearby. One is bronze, and one is iron. You can see, it's still sharp. I've never seen this shape to an arrowhead before. You know, where it's basically three-sided like this. Is that common?

[Non-English speech]
TRANSLATOR: We found lots of these along the wall in this area. These arrowheads are very typical of the Han Dynasty.

[Mysterious music] [Dramatic music] 1,500 years before the Ming, before the Roman Empire formed in the West and Cleopatra ruled Ancient Egypt, the Han Dynasty rose to power. They oversaw a golden age of art, culture, and economic prosperity. They're so well preserved. I'm just amazed. Look at that edge. It's just incredible. The form is just so clear and beautiful.

These tiny arrowheads reveal something momentous—that the wall here is more than 2,000 years old. It's an even earlier Great Wall of China that once stretched for over 6,000 miles. Much of the famous Ming Dynasty wall was simply built right on top 1,500 years later. Battered by desert winds for over two millennia, what remains of this ancient stretch of Great Wall are just fragments of what was once a mighty barrier.

It's kind of hard, just looking at these ruined sections of the wall, to get a sense of what it looked like originally. So using historical sources and archaeological evidence, we've made this pretty phenomenal digital reconstruction of what the wall might have looked like. It's just amazing. Whoa. Look at that.

[Dramatic music] When it was first built, the wall would have stood up to 20 feet high. This thing was enormous. I can only imagine being part of an invading nomad army, and coming up against this wall and thinking, maybe it's better to just go home, because this was formidable.