Archaeologists have discovered evidence of fortified settlements that inhabited the oases of northern Arabia between the 4th and 3rd millennia BC. A team of scientists from the CNRS research centre and the Royal Commission for AlUla recently uncovered a fortification wall surrounding the Khaybar oasis in northwestern Arabia.

The Khaybar oasis fortress, along with the fortified oasis of Tayma, was one of the largest in Arabia during this early period. While other walled oases from the Bronze Age had been documented, this discovery provides new insights into human occupation in northwest Arabia and the complexity of local societies before Islam.

Through field studies, aerial surveys, and architectural analysis, the team estimated the original size of the fortifications. The walls were approximately 14.5 kilometres long, 1.7-2.4 meters thick, and around 5 meters tall.

Today, less than half remains at 5.9 kilometres and 74 bastions, originally enclosing around 1,100 hectares of rural land. Radiocarbon dating of excavated samples dates the construction between 2250-1950 BC.

The Khaybar oasis was part of a network of fortified oases in northwest Arabia. However, the large-scale walls raise questions about why they were built and the nature of the populations. The researchers proposed three main reasons for these monumental desert defences.

First, and most obvious, was physical protection against mobile groups from the desert who could raid settlements. Raiding was a known danger for ancient and early Islamic sedentary groups, but not documented in Bronze Age contexts before.

Second, the walls helped control erosion, soil salinization, and flash flooding – constant threats to agricultural lands.

Finally, the walls visibly marked and demarcated the oasis territory, identifying it with a local authority. This huge construction project emphasized group cohesion while establishing a territorial and social identity.

The researchers conclude the walls were likely built by indigenous populations settling the area to ostentatiously stake their claim. The fortifications would have stood for centuries before later structures replaced them.

This archaeological discovery, published in the Journal of Archaeological Science: Reports, advances the understanding of prehistoric, pre-Islamic and early Islamic societies in northwest Arabia.