Arabian cult may have built 1000 monuments older than Stonehenge

A vast site in north-west Saudi Arabia is home to 1000 structures that date back more than 7000 years, making them older than the Egyptian pyramids and Stonehenge in the UK.

Named after the Arabic word for rectangle, mustatil structures were first discovered in the 1970s, but received little attention from researchers at the time. Hugh Thomas at the University of Western Australia in Perth and his team wanted to learn more about them, and embarked on the largest investigation of the structures to date.

Using helicopters to fly over north-west Saudi Arabia and then following up with ground explorations, the researchers found more than 1000 mustatils across 200,000 square kilometres – twice as many as were previously thought to exist in this area. “You don’t get a full understanding of the scale of the structures until you’re there,” says Thomas.

Made from piled-up blocks of sandstone, some of which weighed more than 500 kilograms, mustatils ranged from 20 metres to more than 600 metres in length, but their walls stood only 1.2 metres high. “It’s not designed to keep anything in, but to demarcate the space that is clearly an area that needs to be isolated,” says Thomas.

In a typical mustatil, long walls surround a central courtyard, with a distinctive rubble platform, or “head”, at one end and entryways at the opposite end. Some entrances were blocked by stones, suggesting they could have been decommissioned after use.

Excavations at one mustatil showed that the centre of the head contained a chamber within which there were fragments of cattle horns and skulls. The cattle fragments may have been presented as offerings, suggesting mustatils may have been used for rituals.

Radiocarbon dating of the skulls shows that they date to between 5300 and 5000 BC, indicating that this was when this particular mustatil was built – and maybe the others too. If so, the monuments would together form the earliest large-scale, ritual landscape anywhere in the world, predating Stonehenge by more than 2500 years.

“This could completely rewrite our understanding of cults in this area at this time,” says team member Melissa Kennedy, also at the University of Western Australia. She says that further south, religious groups became focused in homes, with families displaying small shrines, but the opposite was happening in ancient Saudi Arabia with the mustatils.

There may also have been a relation between the construction of mustatils and the environment. They were built during the Holocene Humid Phase – a period between 8000 and 4000 BC during which Arabia and parts of Africa were wetter, and what are now deserts were grasslands. But droughts were still common, and Kennedy says it is possible that cattle were herded and used as offerings to the gods to protect the land from the changing climate.

Mustatils were typically clustered in groups of two to 19, suggesting that gatherings may have been broken up into smaller social groups.

“The mustatils themselves are probably associated with an annual or generational coming-together of people who would normally be out with their herds and cattle,” says Gary Rollefson at Whitman College in Walla Walla, Washington, suggesting that these rituals were important for bringing communities together. “But there’s no indication that these guys spent a lot of time around the mustatil.”

“These structures are enigmatic,” says Huw Groucutt at the Max Planck Institute for Chemical Ecology in Jena, Germany. He says they show that remarkable human cultural developments took place in the Arabian peninsula.

But despite all the new findings, there is still much to learn. “People are going to understand these structures even more in the future,” says Thomas. “It’s nice to be at the forefront, but we’re also excited to see what other people find.”