Researchers believe they have figured out how ancient Egyptians were able to transport heavy stones across the hot desert to build pyramids: wet sand.

Physicists determined that workers most likely put the stones on a sledge and then saturated the sand under it in order to move the stones.

Research was conducted by the Foundation for Fundamental Research on Matter (FOM) and the University of Amsterdam, according to a release issued by the university.

Making the sand wet reduced the amount of sliding friction when sledge was being moved over it, compared to moving an object over dry sand.

This was a popular method, as it was labor efficient and made stones easier to move, according to a news release.

It required fewer workers to transport the rocks if the correct amount of water was applied to wet the sand. If too much water was used, the sand grains would clump together and pile up in front of the sledge, according to the release.

Researchers believe that the discovery could provide some insight into modern day applications when it comes to moving granular materials, like sand, and the transportation of concrete coal and asphalt.

The method was confirmed by an ancient Egyptian wall painting found in the tomb of Djehutihotep.

The painting depicts a person pouring water in front of sledge carrying a large statue, according to the release.

Research was published this week in the journal Physical Review Letters.

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