A Buddhist mural dated to around the seventh century A.D. is one of many in Afghanistan's Bamian Valley that were recently found to contain oil- and resin-based paints.

The use of the substances at such an early date is a surprise, since they require sophisticated knowledge of chemical properties, scientists say.

Oil is used in paints to help fix dyes and help them adhere to surfaces. It also changes a paint's drying time and viscosity.

Europeans began using oil in their pictures by about 800 A.D., but the new research on the Central Asian pushes back the onset of oil-based painting by at least a hundred years.

Researchers hope to find even earlier examples by studying other Central Asian sites.

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