Dozens of Egyptian pyramids probably built along the lost arm of the Nile

According to a new study, 31 Egyptian pyramids were built on the banks of a now defunct arm of the Nile River. This explains the strange location of the group of pyramids on a narrow piece of land in the middle of the Western Desert Plateau, as most ancient Egyptian settlements were located in close proximity to the river. The Nile has been Egypt's main transport artery throughout history, so it makes sense that a large construction project would be located on the bank where ships were unloaded, rather than tens of kilometres away in the middle of the desert.

The most famous Egyptian pyramids are located in this area, such as the Giza pyramid complex, the Djoser stepped pyramid, the Broken Pyramid, and so on. They were built between 2700 and 1700 BC. At the end of the Ice Age (the period of the greatest glaciation of the Earth), there was much more moisture in Africa, and the level of the Nile was significantly higher. According to the scientists, at that time there was an approximately 64-kilometre-long arm of the Nile. To confirm their hypothesis, the scientists studied satellite images, sedimentary rock samples, and conducted geophysical surveys on the Western Desert Plateau. They propose to name the lost riverbed "Ahramat", which means "pyramids" in Arabic.

The researchers also noticed that many of the pyramids have paved roads that end at the point where the riverbed was lost. The paved roads near the pyramid complex at Giza (Chephren, Menakure and Kentkauz) lead researchers to the conclusion that this place was the mouth of a dried-up river arm, so it still existed during the Fourth Dynasty of the Old Kingdom.

Scientists believe that a drought that occurred about 4,200 years ago turned the arm into a shallow river without a strong current, and the wind was able to gradually fill it in, making it invisible to optical satellite images. The knowledge of the existence of this arm will now give us an understanding of where else settlements of that era can be rotated to save them from urbanisation.

The Egyptian pyramids are the hallmark of modern Egypt, and they have preserved a great deal of information about the development of one of the oldest civilisations on Earth. The seasonality of the Nile flood meant that people could not farm for several months of the year. This freed up a large amount of labour, which the authorities used for monumental construction projects.

The study was carried out by a team of researchers from the University of North Carolina Wilmington, led by Eman Ghoneim.