Researchers Discover Why Egypt’s Pyramids Were Built Along the Now-Vanished Ahramat Branch of the Nile

The vast fields of pyramids in Egypt are concentrated along a narrow desert strip, yet until now, no convincing explanation has been given for why these pyramids are grouped in this specific location.

In a recent study, researchers used radar satellite images, geophysical data, and deep soil surveys to investigate the subsurface structure and sedimentology in the Nile Valley next to these pyramids.

They identified segments of an ancient extinct branch of the Nile, which they call the Ahramat Branch, running along the foothills of the Western Desert Plateau, where most of the pyramids are located. Many of the pyramids, dating from the Old and Middle Kingdoms, have causeways leading to this branch and end with Valley Temples that might have served as river ports along it in the past.

The watercourse of the ancient branch of Ahramat. Credit: Eman Ghoneim et al.

The researchers suggest that the Ahramat Branch played a crucial role in the construction of these monuments and that it was active simultaneously, serving as a waterway for transporting workers and building materials to the pyramid sites.

The data analysis reveals that the Ahramat Branch had a high water level during the early part of the Old Kingdom, especially during the Fourth Dynasty, while this water level significantly decreased during the Fifth Dynasty. This trend aligns with previous studies indicating a high Nile flow during the Fourth Dynasty.

However, in the Middle Kingdom, although previous studies implied abundant Nile flooding with occasional failures, the analysis shows that all pyramids from this period were built much further east of their Old Kingdom counterparts, at lower elevations and closer to the floodplain. This could be explained by the eastward migration and gradual abandonment of the Ahramat Branch before the construction of the Middle Kingdom pyramids.

The inlets of Sakkara and Dahshur are connected to the Ahramat branch. Credit: Eman Ghoneim et al.

The eastward migration and abandonment of the Ahramat Branch could be attributed to the gradual tilting of the Nile delta and floodplain towards the northeast due to tectonic activity, as well as windblown sand encroachment due to the branch’s proximity to the Western Desert Plateau. The increased sand deposition during the end of the Old Kingdom and throughout the First Intermediate Period was likely linked to the period of drought and desertification of the Sahara.

Additionally, the reduction in river flow caused by decreased rainfall and increased aridity in the region would have gradually reduced the watercourse’s capacity, leading to the silting up and abandonment of the Ahramat Branch as the river migrated eastward.

Sediment data from the bed of the Ahramat Branch, collected from the two deep soil surveys, show an abrupt change from well-sorted medium sands in depth to overlying finer materials with layers including gravel, shells, and manufactured materials. This indicates a sharp shift from a more consistent higher-energy depositional regime to a generally lower-energy regime with periodic flooding.

According to the researchers, mapping the hidden course of the Ahramat Branch has allowed us to reconstruct a more complete picture of Egypt’s ancient landscape and a potential water transport route in Lower Egypt, in the area between Lisht and the Giza Plateau. Revealing this extinct Nile branch can provide a more refined idea of where ancient settlements were possibly located in relation to it and prevent them from being lost due to rapid urbanization, thereby improving measures for the conservation of Egypt’s cultural heritage.

Sources

Ghoneim, E., Ralph, T.J., Onstine, S. et al. The Egyptian pyramid chain was built along the now abandoned Ahramat Nile Branch. Commun Earth Environ 5, 233 (2024). doi.org/10.1038/s43247–024–01379–7