The pharaohs ruled their empire for hundreds of years, spreading culture, architecture and the arts before it collapsed into economic ruin. Why that happened is one of the great mysteries of history.
Now a team of scientists from Scotland and Wales believe the answer lies beneath the waters of Lake Tana, high in the Ethiopian Highlands, and the source of the all-important Blue Nile.
Samples taken over the past two years from sediments beneath Tana, which supplies the water which makes the lower Nile valley so fertile, reveal the lake may have almost dried up during the critical period around 4,200 years ago due to climate change.
I'd thought evidence for drought around the region near the end of the OK was fairly well demonstrated. See here for instance.