Why the ancient Egyptians built most of their pyramids on what is now a narrow, inhospitable strip of desert has long puzzled archaelogoists.
However it seems scientists may finally have an answer, after they uncovered evidence that suggests pharaoh’s tombs were originally sat next to a 40-mile branch of the River Nile.
It however appears the once crucial artery for commerce, culture and building material vanished centuries ago, reports The Times.
The waterway is now buried but was uncovered using satellite imaging, geophysical surveys and the discovery of buried river sediment.
When the construction of the pyramids began about 4,700 years ago, the branch would have run parrellel to the west of the current course of the Nile.
Researcher Eman Ghoneim from the University of North Carolina Wilmington believes the branch would have been used to bring in materials and labourers.
She said: “We were surprised at just how large this branch of the Nile once was — at points it would have been half a kilometre wide and 25 metres deep.”
There had previously been “no convincing explanation” for the location of the pyramids.
Ghoneim and her colleagues, writing in the journal Communications Eart and Environment, have proposed naming the lost section of river the “Ahramat Branch”, with ahramat the Arabic for pyramids.
Researchers exmained aportion of land in the northern Nile Valley in Egypt.
The patch, between Lisht in the south and the Giza Plateau in the north, saw 31 pyramids built over a period of almost 1,000 years. They now sit on the edge of the Western Desert, which is part of the Sahara.
Ghoneim thinks the lost section of river could have been used to transport building materials, including granite, from Aswan, some 500 miles south of Giza.
She also says that many pyramids dating to the Old and Middle Kingdoms have causeways leading to the lost branch. These often lead to structures that could have acted like harbours.
The researchers suggest the build-up of windblown sand, which was linked to a major drought 4,200 years ago, was one of the reasons the waterway began moving east before vanishing.
Having studied satellite images, the researchers used geophysical surveys and sediment cores to confirm the presence of river sediment beneath the modern land surface.
Ghoneim told The Times the findings show just how much of a role the Nile played in the growth and expansion of ancient Egyptian civilisation.
She said: “It served as a lifeline in a largely arid landscape. And it provided a route or a water corridor that allowed for the transportation of goods and workmen and building materials.”
The study says the evidence suggests the branch was “active and operational” while the pyramids were being built. It adds: “This waterway would have connected important locations in ancient Egypt, including cities and towns, and therefore played an important role in the cultural landscape of the region.”