The old Sui-Tang Canal stretched from a patch of river near Luoyang, the old Tang dynasty capital, all the way to the lakes that dot the hinterland north of Nanjing. Effectively, it linked the Yellow River with the Yangtze, consolidating that massive inland trade network that allowed for water transport.

I have heard of the Grand Canal, but the one I associate with China goes from north to south, linking Beijing to the Yangtze. But this one was just as huge an enterprise, heading from west to east in a south-easterly direction. It is also almost entirely forgotten. The Chinese can only guess at the route of the Sui-Tang canal. Occasionally, they luck into a section of it, and can extrapolate its rough bearings. But after being built in the 600s, and flourishing for several hundred years, it fell into disrepair after the Song dynasty, when the capital of China shifted north to Beijing.

One of its docksides has been uncoverd in the small village of Liuzi, host to archaeologists since 1999. A Dutch-barn roof sits over the pit, where two metres below centuries of accumulated grime and soil, they found the large flagstones of a canal docks. During the middle ages, this was a site of frenzied bargaining, busy unloading, possibly even a bridging point. There are forgotten longboats, scuttled in the mud, and an entire sedimentary layer of Tang-dynasty porcelain. The site leader shows me a ceramic Tang lion in sancai tricolour ware, and a Jin-period statuette of a child in the lesser known red-and-blue ware. It’s the first time I can remember even seeing something that could be described as properly “Jin” – the name is used for the nomads who conquered north China and pushed the Song to the south, but the piece points to an era where north China blundered on its own path, applying its skills to new markets and new customers.

It is a difficult take. We are losing the light and there are only mere minutes before the sun will go behind the nearby houses. The director wants me walking and talking, and we have to go to and fro about the usual points of data – how to describe the Sui-Tang era in two seconds for an audience that doesn’t know its dynasties? Repeatedly, I refer to “the sleepy town of Liuzi,” only to be interrupted by a blast of truck horns as big-rigs turn off the highway. I resort to referring to “the sleepy town of Liuzi, CLOSE TO THE HIGHWAY” just in case we lack any clean takes at all. It makes me angry, because this is a rare occasion where I get to stand in an actual archaeological site, talking about actual archaeology.

Back to the hotel to film me turning on a television set. It will be the opening shot of the Theatre episode, for which all the footage is now banked. We are only four days away from wrapping, but the other five episodes all have pick-ups that will need to be crammed in.

Jonathan Clements is the author of The Emperor’s Feast: A History of China in Twelve Meals. These events featured in Route Awakening S02E06 (2016).