In northern Medina, at the heart of the Harrat Khaybar volcanic field in Saudi Arabia, archaeologists have made a startling discovery: a lava cave, known as Umm Jirsan, was occupied by humans at least 7,000 years ago, and possibly even 10,000 years ago.
Located about 78 miles (125 kilometers) north of Medina, Umm Jirsan is the longest known lava tube in Arabia today, with passages stretching approximately 4,865 feet (1,481 meters). Evidence of human presence in this lava tube, which has been preserved despite the region's aridity, includes fragments of fabric, worked wood, as well as human bones and depictions of domestic animals like sheep and goats.
Carbon dating and optically stimulated luminescence dating indicate that the site has been used for millennia, up to a relatively recent period. These findings suggest that Umm Jirsan served as a temporary refuge rather than a permanent dwelling. It likely lay on ancient transhumance routes, providing shade and water access to passing shepherds and their flocks.
Possible identification of species in Umm Jirsan's rock art, including (A) sheep; (B) a goat and two figures with tools at their belts; (C) long-horned cattle, digitally enhanced photo; and (D) an ibex with striated horns and markings on the fur.
Below: sketches of examples A-D.
Credit: Stewart et al., 2024, PLOS ONE, CC-BY 4.0 Chemical analysis of human remains shows an increase in plant-based foods such as cereals and fruits over time, likely due to the rise of oasis agriculture in the Bronze Age. This analysis also demonstrates that the lava tube played a key role in local economies, tied both to transhumance and hunting.
The formation of lava tubes, resulting from underground passages created by flowing lava, offers a natural shelter. Thus, researchers even suggest that future astronauts could use similar structures on the Moon as shelters.