The largest pyramid chain in Egypt is concentrated along a narrow strip of desert. Yet, there is no convincing explanation for why these structures are clustered in this area.

Ancient Pyramid Complex

During the past few millennia, the landscape of the northern Nile Valley in Egypt underwent several hydrological and environmental changes. Approximately 10,000-6,000 years ago, freshwater marshes were common within the Nile floodplain.

By the time of the Old Kingdom Period, early pyramid complexes were built at the margins of the floodplain. Between 4,700 and 3,700 years ago, 31 pyramids - including the pyramids of Giza - were constructed along a now inhospitable desert strip in the Nile Valley between Giza and the village of Lisht. These places are currently several dozens of miles away from the Nile River.

Archaeologists used to believe that ancient Egyptians relied on a nearby waterway to move the gigantic materials used in pyramid construction. They could have also used this waterway to build other enormous structures, like valley temples. However, they are not certain of the mega waterway's location, size, shape, or proximity.

Experts also think that the Nile River was split up into several more branches than are present today. It was also previously speculated that one of these branches may have flown by the Giza-Lusht chain, although there is a lack of concrete proof to support this idea.

READ ALSO: Buried In Time: Another Ancient Pyramid Discovered In Egypt

Unearthing a Long-Buried River Branch

In a recent study, an international team of researchers explains why these pyramids are concentrated in what is now a narrow, inhospitable desert strip. The details of their study are discussed in the paper "The Egyptian pyramid chain was built along the now abandoned Ahramat Nile Branch."

Led by Eman Ghoneim from the University of North Carolina Wilmington, the researchers studied satellite imagery to locate the possible location of a former Nile River branch. They used geophysical surveys and deep soil coring to confirm the existence of ancient river sediments.

The team claimed to have identified portions of a major section of the Nile River, which they called the Ahramat Branch. Evidence of this branch is currently buried under farmland and desert, but it is thought that the waterway once ran along the eastern part of the Western Desert Plateau (WSD) just to the west of the modern Nile.

The 40-mile-long course of the Ahramat Branch appears to flow closely past the pyramid complex, which also lies along the eastern region of the Plateau. It is suggested that the Ahramat Branch was simultaneously active and played a vital role in transporting construction materials to the sites.

The researchers also discovered that many of the pyramids had causeways that ended at the proposed riverbanks of the Ahramat Branch. The enormity of the waterway and the termination of the pyramids' causeways imply that this long-lost branch was in operation while the pyramids were being built.

Around 4,200 years ago, a major drought began in the region, resulting in an increased build-up of windblown sand. This could have caused the eventual disappearance of the Ahmarat Branch.

RELATED ARTICLE: Pyramids of Giza Mystery: What Was Found Inside and Why Were They Built

Check out more news and information on Pyramid in Science Times.