Discovery of extinct river may solve mystery of Egyptian pyramids' location (2024)

There is an oddity about the pyramids in Egypt. A chain of them runs along a narrow strip of the desert, parallel but not adjacent to the Nile. In fact, this cluster featuring some of Egypt's earliest pyramids lies several kilometers from the river.

The question is why they were built there – a choice that has puzzled researchers sorely, given the river's centrality to life and transport of workers and materials, as shown in ancient Egyptian art.

The answer may be that they did lie near the river, but not the Nile. These pyramids were erected starting about 4,700 years ago along an extinct branch of the Nile, researchers propose.

At its heyday, that branch wasn't some little stream but a major waterway that could have served to build the largest cluster of pyramids known in Egypt. The Ahramat was between 2.5 and 10.3 kilometers west of today's Nile (1.5 to 6.5 miles), between 2 to 8 meters deep, about 64 kilometers long and 200 to 700 meters wide – which is pretty much the same as the Nile today, the team says.

The new theory, based on finding stretches of the waterbed of the extinct Ahramat Branch ("Pyramids" Branch in Arabic) in proximity to these pyramids, appeared Thursday in Communications Earth & Environment. Signs of the forgotten branch were found using radar satellite imagery combined with geology and deep-soil cores, explain Eman Ghoneim of the University of North Carolina Wilmington, Mohamed Fathy of Tanta University, Egypt, with colleagues.

The long-lost Ahramat Branch runs along the foothills of the Western Desert Plateau, and that is exactly where the majority of the pyramids lie, the team writes. Moreover, they detected canals connecting the Ahramat Branch with the Valley Temples – which, ritual purposes aside, may have acted as river harbors.

In short, they postulate that the pyramids arose along the Ahramat Branch, which served the purpose the Nile was thought to have: to transport materials, mankind and beasts of burden for the pyramids' construction.

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Among the structures along the Ahramat, the team notes the "Bent Pyramid" built by Snefru (aka Soris), the founding pharaoh of the Fourth Dynasty, which predates the Giza pyramids and was beautifully preserved – all the better to confound researchers as to why it had been erected in the deep desert, far from the Nile floodplain. Now they think they know why, stressing, for instance, a 700-meter canal paved with limestone blocks connecting the Bent Pyramid to a valley temple (i.e., what the researchers think is a river harbor).

The roaring rivers of the Sahara

What was this unknown Ahramat Branch, and what happened to it? The answer lies in the extreme environmental changes the Sahara desert (and Arabia) periodically experience, mostly recently in the Holocene. Every 21,000 years, North Africa and Arabia turn green and, starting about 14,000 years ago, it happened again – a time known as the African humid period.

From hyper-arid desert, wide swaths of the Sahara and Arabia became lush, with large river systems and lakes. "The wet conditions of the Sahara provided a suitable habitat for people and wildlife," the team writes.

Actually, the Nile Valley itself was virtually uninhabitable. This is because sea levels were rising as the glaciers in the far north retreated, rainfall increased sharply and, long story short, the Nile was high and its valley was swampy. Not a nice place to live at all unless one is a hippo.

Rather, as the Nile waters burgeoned and roared, fed by heavy rainfall (from 300 to 900 millimeters a year) in the eastern Sahara where Egypt is, people moved to the dry still-desert margins of the Nile Valley, the researchers explain based on prior work. Meanwhile, the rising Nile developed channels branching across the floodplain. The Ahramat could have been a tributary flowing into the Nile from another river, they add.

And as the humid period came to a staggering close about 5,000 years ago and the Sahara dried out again and rainfall sharply diminished, people moved from the drying desert to the Nile Valley and settled along the edges and on elevated areas on the floodplain, the team explains.

Come the start of the Old Kingdom 4,686 years ago – as the first pyramids, including the great Step Pyramid of Djoser, were rising on the edge of the floodplain – the river waters were still high, especially during the wet episodes that still occurred.

Over the centuries and millennia since the re-aridification of the Sahara and reoccupation of the Nile Valley, the course of the mighty Nile migrated, as river courses do, and branches and tributaries silted up, moved and/or disappeared. Thus, today we have major ancient Egyptian sites that are far from the banks of the Nile where it is today.

Finding extinct riverbeds in Egypt has been hampered over the years by modern development as well as silting and shifting sands, the authors explain. A number of studies, however, have identified buried channels in the Nile Delta region – for instance, one from about 7,000 to 5,000 years ago near Memphis, and a branch from the New Kingdom era by Luxor.

Now the new study brings long, previously unknown stretches of buried riverbed that can explain why no less than 31 pyramids were built in the deep desert. The pyramids in question date to the Old Kingdom and the Second Intermediate Period, they say: 4,686 to 3,649 years ago.

So what have we? The discovery of stretches of extinct river that may explain why (and how) giant pyramids were built deep in the desert, miles from the Nile. The Bent Pyramid, for one, was built by a channel some 200 meters wide, off the Ahramat Branch. The Red Pyramid is right near it, built by the same early pharaoh.

Come the Middle Kingdom, more pharaohs would build the so-called Black Pyramid, White Pyramid and Pyramid of Senusret III, a kilometer or more to the east of the Bent and Red pyramids. Why? Because the Ahramat Branch had shifted eastward after the Old Kingdom – possibly due to silting, possibly due to tectonic activity tilting the land. Rivers move.

Their theory is that during the Old Kingdom period, the Nile was high and the Ahramat Branch was too, especially during the time of the Fourth Dynasty. Then the water level fell significantly during the time of the fifth and sixth dynasties, they say.

"In the Middle Kingdom, although previous studies implied that the Nile witnessed abundant flood with occasional failures, our analysis shows that all the pyramids from the Middle Kingdom were built far east of their Old Kingdom counterparts, on lower altitudes and in close proximity to the floodplain as compared to those of the Old Kingdom. This paradox might be explained by the fact that the Ahramat Branch migrated eastward, slightly away from the Western Desert escarpment," the team writes.

And now it is gone – almost. The team says the marshy Dahshur Lake, southwest of the city of Dahshur that is home to the Red and Bent pyramids, is most likely the last existing trace of the course of the once mighty Ahramat Branch.