The researchers were able to date the construction of one of these structures 7,000 years ago, using radiocarbon dating.
In the last decade, various discoveries have been made at archaeological sites in Saudi Arabia. And one of the most enigmatic is the presence of millions of stone structures in the west of the country, ranging from burial tombs to hunting traps.
Some of them consist ofvast rectangular shapes, called by archaeologists ‘mustatils’, the Arabic equivalent of "rectangle."
Mustatils are only found in northwestern Saudi Arabia. They had previously been recognized from satellite images and, as they were often covered by younger structures, it had been speculated that they could be ancient, perhaps from the Neolithic.
In a new article published in The Holocene, researchers from the Max Planck Society in Jena, Germany, along with Saudi and international collaborators, presented a first detailed study of Mustatils. Through a combination of field studies and analysis of satellite images, the team was able to greatly expand their knowledge of these enigmatic stone structures.
More than 100 new mustatils have been identified around the southern fringes of the Nefud Desert, joining hundreds previously identified in Google Earth imaging studies. The team found that these structures typically consist of two large platforms, connected by long parallel walls, sometimes reaching more than600 meters in length.
The long walls are very low, do not have visible openings and are located in various landscape settings. Archaeologists note that only a few other objects, such as stone tools, have been found in the vicinity. Together, these factors suggest that the structures were not simply utilitarian entities for something like storing water or animals.
In one location, the team was able todating the construction of a mustatil to 7,000 years ago, by radiocarbon dating of the charcoal inside one of the platforms. A set of animal bones was also found, including both wild animals and possibly domestic cattle. In another mustatil, researchers found a rock with a geometric pattern painted on it.
When Arabia was not a desert
The fact that several of these structures were sometimes built side by side may suggest that the very act of their construction was a kind of exercise in social bonding.
“Our interpretation of Mustatils is that they are ritual sites, where groups of people gatheredto carry out some kind of social activities currently unknown, ”explained Huw Groucutt, team leader. "Maybe they were places of animal sacrifice or parties."
Northern Arabia was 7,000 years ago very different from what it shows today. Rainfall was higher, much of the area was covered by grasslands, and there were scattered lakes. The shepherd groups thrived in that environment. However, it would have been a challenging place to live, with droughts a constant risk.
The team's hypothesis is that mustatils were built as a social mechanism for living in this challenging landscape. While they are not the oldest buildings in the world, they do have an exceptionally large scale for that early period,more than 2,000 years before the pyramids began to be built in Egypt.