This is an hour-long programme made for the PBS Nova Series about the European looking mummies discovered in the Taklamakan Desert. The mummies are unusual in that they simply survived because of the extreme dryness of their burial ground in the desert.
The Kingdom of Lou-lan was an ancient Buddhistic kingdom which used to house 4,000 monks, a quarter of the population, but the remains are sparse indeed, as it disappeared into the desert it arose in, long ago.
The Dark Castle of the title refers to the fortress at Khara-khoto, which was a main center of the Tangut state. The Castle has legendary status amongst the local people, who fear to go there, but the crew find some guides and trek across the desert on camels.
This episode focuses on the magnificent Mo-gao caves at Dun-huang in the Gobi desert. In this complex, there are 500 caves and over 3,000 statues and murals. It is counted as the longest art gallery in the world.
This episode sees the expedition crossing first the Yellow River, with its goat-skin rafts and giant waterwheels, and entering the Gobi desert along the He-xi corridor, where it visits some of the main citadels along the route.
The first episode in the series focuses on Chang-an, which in modern-day China is called Xi-an. It was formerly the capital of China and the source of the Silk Road which ran from there to Rome. In ancient times it was the largest city in the world.