We may be getting closer to why hundreds of great stone structures were built in the deserts of northwestern Saudi Arabia thousands of years ago.
According to a new in-depth analysis, the mysterious rectangular enclosures were used by Neolithic people for unknown rituals, depositing animal offerings, possibly as ex-voto to one or more unknown deities. Excavations revealed hundreds of fragments of animal remains, clustered around a vertical stone slab interpreted as sacred.
The roughly 7,000-year-old monuments known as mustatils (an Arabic word meaning rectangles) have baffled archaeologists since they came to scientific attention in the 1970s.
It wasn’t until 2017, however, that the full extent of their spread across the Arabian Peninsula was revealed in the first scientific paper document their discovery. Aerial surveys have identified over 1,600 mustatils, sometimes in groups, scattered throughout the desert.
Nicknamed “gates” because of their airy appearance, mustatils were described in this article as “two short, thick lines of piled up stones, roughly parallel, connected by two or more much longer and thinner walls.”
They consist of two short, thick platforms, connected by much longer low walls, measuring up to 600 meters (2,000 ft), but never more than half a meter (1.64 ft) high.

But often collapsed, oboth ends short forms one entrance, while the other contains rooms of varying size. It is not known what these chambers were used for, but there is a curious absence of tools in and around them.
Aarchaeologists believe tits feature set suggests that their use was not useful; the low walls and lack of roofs would make them unsuitable as cattle pens or warehouses, for example.
What they may contain in some cases are dressed and decorated stone slabs, as well as a scattering of animal bones. A number of mustatils also feature a long court, evoking a processional element.
In 2019, an international team of scientists led by archaeologist Melissa Kennedy from the University of Western Australia excavated a 140-metre-long sandstone mustatil near Al-‘Ula, named IDIHA-F-0011081, collecting fragments of material and cataloging the different features of the monument.
At the head of the mustatil – the short end with chambers – they found a space with standing stone slabs. They also collected 260 fragments of animal bones, teeth and horns, mostly clustered around the stone slab.
They identified 246 of these fragments; and, more intriguingly, the bone pieces were exclusively pieces of animal skulls, taken from goats, gazelles, small ruminants and domestic cattle.

Some show signs of cut marks; others show signs of burning.
This, the team says, suggests that the stone slab is what is called a betyle – a sacred stone representing the god or gods of the people who lived in the area thousands of years ago, with heads of animals placed as ritual offerings.
These menhirs are not found in all mustatils, but enough, according to researchers, to be significant.
“We hypothesize that the standing stones (betyls) of mustatil IDIHA-F-0011081…may have functioned as a mediator between humanity and the divine, acting as a proxy or manifestation of an unknown Neolithic deity/deities or of a religious idea, to which the faunal elements were deposited as votive offerings”, they write in their diary.
“Due to the number and age of slaughtered animals and the presence of fragile cranial elements suggestive of fresh skulls and anthropogenic marks indicative of specific processing practices, we hypothesize that ritual feasts also played a role in mustatil IDIHA-F-0011081.”

Radiocarbon dating shows a range of dates, suggesting the site was in use for a long time, from around 5307-5002 BCE, to 5056-4755 BCE.
And there is another curious clue indicating the use of the monument in ancient society: a small rectangular stone chamber, in which researchers found human remains, next to the mustatil’s head, where the chamber was. betyle. It’s a cistus; a small ancient burial chamber, built of unworked sandstone slabs. It had collapsed on itself over time, but still contained broken and partially jointed human remains.

Time had done its work on these bones as well, but Kennedy and his team were able to determine that the deceased was an adult male who likely suffered from osteoarthritis. Who he was and why he was buried at mustatil remains unknown; but there is something a little special in the burial.
The mustatil itself was relatively hidden in the sandstone canyons, but the human remains were deposited several hundred years after the animal remains. This suggests that the site remained important long after it was no longer in use, and may have been a site of pilgrimage, or at least shrine visitation.
“The proof of [the site] suggests that the mustatil tradition was characterized by the intersection of belief and economic ways of life”, the researchers to write.
“The incorporation of these two facets suggests a deeply rooted ideology tanglewhich was shared over a vast geographic distance, indicating a much more interconnected landscape and culture than had previously been assumed for the Neolithic period in northwestern Arabia.”
The research was funded by the Royal Commission for AlUla and has been published in PLOS ONE.