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Researchers confirmed a total of six different fortified walls surrounding a network of oases in the northwest Arabian Desert.

The oldest wall is upwards of 5,000 years old, with some new finds dating back 4,000 years.

Experts claim the walls show community structure, not just a defensive mindset.

Researchers discovered that an Arabian Desert oases environment had a full network of walled fortifications over 4,000 years ago, not only showing off defensive insight, but also socioeconomic development of an expansive Arabian Peninsula civilization.

A new study published in Antiquity confirmed four new walled oases coming as part of a network that now boasts six confirmed walled oases structures in the northwest Arabian complex. “The recent identification of a walled oases complex in northwest Saudi Arabia signals a radical shift in our understanding of the socioeconomic evolution of this vast, largely unexplored region,” the study authors wrote.

A walled oasis protected not only the critical water source, but settlements within, likely full of goats and sheep, as well as crops of grains, fruit trees, and even date palms. “Outer walls, serving as a display of power as well as a means of protection,” the authors wrote, “required substantial investments form local populations not only for their initial construction but also for maintenance and modification over time.”