The uniformity of the chisel work is impressive, it looks as if it’s been done by just one person, but that seems unlikely given their size. Whether the neat curved lines were produced as a by-product of the excavation method or as purposeful decoration is unclear.

‘Cave 1’ as it is creatively known, is now open for tourists. The walls have primitive carvings of a horse, fish and bird, possibly symbolising earth, water and air.

Another of the cave’s mysteries is that there’s no evidence of lighting being used. In similar caves of the region, for instance Flower Mountain Grottoes in Huangshan City, there are the remnants of lamp bases, oil plates and other lamp equipment. In Longyou there were no such traces, and they must have needed to see what they were doing when they were excavating. The entrances are small and the caves deep so there would have been little to no natural light.

The grotto had been under water for a good long time, but apparently carbon staining from fire is incredibly stable and should still have remained visible.

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