2,000-Year-Old Cliff Paintings in Southern China Are Still Bleeding Red

Along the limestone cliffs of southern China's Zuojiang River valley, thousands of red figures have looked out over the water for roughly 2,000 years: drums, bells, animals, people, pregnant women. Monsoons and typhoons should have scrubbed them away long ago. Researchers suspect the paint may have been made with blood.

Writing in the Journal of Archaeological Science, the team examined fallen fragments of the Huashan rock art, a UNESCO World Heritage Site covering more than 80 locations along roughly 160 miles (260 kilometers) of river. The artists appear to have heated animal bones or bird droppings with limestone or shells, then stirred in water and blood to make a pale primer, painting red clay over it. As the lime cured, the blood proteins helped lock the pigment into new mineral crystals. The bond is so strong that when the paint peels, the cliff comes off with it. The team needed an electric drill to separate the layers.

Then it gets stranger. At one site, about 97 percent of the blood proteins were human; at another, roughly half. The human blood carried two proteins found at high levels in pregnant women, and the researchers suspect it was collected during or after childbirth. The paintings themselves show pregnant women and sex scenes. The artists are believed to be the Luoyue, a matrilineal people, and the team speculates the blood served fertility rituals.

Not everyone is persuaded. Outside experts warn the faint human signal could be lab contamination, note that those proteins also show up in people who aren't pregnant, and point out that no ancient DNA was recovered to say whose blood it was.

The paint survived two millennia of typhoons. Whether the childbirth theory survives a contamination check is another matter.

Read the full story at Smithsonian Magazine, August 25, 2026

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