I’m finding it a little bit difficult to breathe. Kunming is a mile above sea level, which makes itself felt in the time it takes to boil water, the dryness of the air, and the fact that I am out of breath after racing up a flight of stairs. But it is a wonderfully clean city, there are lot more pretty girls here than in most other parts of China (our director says the boys are good-looking, too), and the people are oddly friendly. At one point today we were mobbed by ten policemen, who had not been informed that we would be filming outside the museum, but they were all very polite and smiley, and once our credentials were proven, bent over backwards to help us, stopping the traffic and even giving our sound man and his gear a lift to the entrance.

The new Yunnan Provincial Museum glows red-gold in the sunrise. It has been designed, supposedly, to resemble the famous Yunnan Stone Forest. But it is packed with materials from the culture that once flourished on the shores of Lake Dian, which had largely faded from view by the end of the Han dynasty.

Nothing survives of the Dian people but the stories about them in the Grand Scribe’s Records, and whatever has been pulled out of their graves. And with the caveat that the graves reflect the lives and attitudes of the ruling elite, it shouldn’t surprise us if their artefacts come across as a bit, well, cruel. The Dian kingdom, at the time it was assimilated into the empire of the Han Chinese, was home to a peaceful race of cattle herdsmen, ruled over by an equestrian elite who seemed to take an odd pleasure in depictions of violence.

Their shell kettles (cowrie shells were money) come decorated with intricate battle scenes, featuring captives being dragged away for sale, victims pleading for their lives, and a wounded man crawling from the battlefield, unaware that a mounted cavalryman is bearing down on him. In one of the tableaux, an enemy soldier appears to have the upper hand, not seeing the man on the other side of the battlefield taking aim with one of those new-fangled crossbows.

The glee in which the Dian seemed to take in the suffering of others is repeated throughout their artefacts. Twin spearheads feature decorations of dangling slaves, hanging by their wrists. Belt buckles feature scenes of boars fighting panthers, and lions locked in combat. The most famous Dian artefact is a low bronze ritual table in the shape of a cow being mauled by a tiger, and yet still standing protectively over its calf.

Several archaeologists have suggested that the Cow and Tiger Table is loaded with symbolism – that the cow represents the locals, while the tiger stands for their horrid overlords, and the calf for local traditions that refuse to be snuffed out. The rulers of Dian, it has been suggested, were originally a band of Scythians, pushed out of Central Asia around 200 BC, who lorded it over the locals in Yunnan until the Chinese turned up to turn the tables.

The Dian themselves disappeared from history around the time that the Grand Scribe’s Records wrote them up. They were invaded by warriors from Chu in the late Warring States Period, and the victorious general was just about to report home when Chu fell to the First Emperor. Rather than return to an uncertain future, he turned his army around and settled by the Expansive Lake (Dian), and his soldiers soon faded into the local population, whose former style favoured dreadlocked horsemen, barefoot in all statuary and carving, tattooed with writhing snakes. They enjoyed what UNESCO still describes as the most biologically diverse region in the world, spanning the upper reaches of the Yangtze (here known as the Golden Sands), the Mekong (here known as the Lancang) and the Salween (here simply called Nu, the Angry River). Since the Red River, which goes all the way to Hanoi, also rises here, the Dian kingdom sat the crossroads of several major cultures, trading with the Shu and Ba kingdoms of Sichuan, with what is now Vietnam, and towards the west.

Fan Haitao, who set up the Dian gallery in the Yunnan Provincial Museum, takes me through a small selection of the foreign objects dug up locally, including a buckle representing a winged lion (lions, winged or otherwise, being unknown in China back at that time) seemingly from Persia or Afghanistan, agate beads from Pakistan, and glass from India.

“Our biggest find,” he reveals, “was at a place called Yangfutou, which was under the flight path of the Flying Tigers.” The American mercenary airmen, famously posted to Yunnan to make life miserable for the Japanese, used to fly over a low hill near their base, and observe that it was a nice place to be buried. Yangfutou was turned into a graveyard for the Flying Tigers, which was when diggers started to unearth strange objects. It was not, however, until 1999, that Yangfutou revealed its greatest treasure, the grave of a forgotten Dian nobleman, complete with cowrie shell moneybags, bronze drums, and fiendishly decorated weaponry.

“The grave was under the water table,” he tells me, “so it was completely waterlogged. This meant that we didn’t just get the bronze, but some wooden pieces and the lacquerwork ancestors.” He points at a series of animal-headed dildos, the word “ancestor” also meaning “penis” in Chinese.

So, I ask innocently, what were they used for?

“I think,” he says carefully, “they had a… ritual quality.”

Why are they so small, I ask, pointing at the largest one, which is truly massive. But we can’t use the footage, because the crew was giggling so much at the look on his face.

Jonathan Clements is the author of A Brief History of China. These events featured in Route Awakening S05E03 (2019).