An international team led by an Egyptian researcher was able to give an explanation of an epic migration by the inhabitants of the Nile Valley about 10 thousand years ago, as they moved away from the vicinity of the great river for about 3 thousand years, and then humans returned to it again.

In his statement to Al Jazeera Net - via the Zoom application - Abdullah Zaki - a researcher in the Department of Earth Sciences at the Swiss "University of Geneva" and is the main author of the new study - says, "Previous research in this area indicated that the residents of the Nile Valley had migrated away from The river in the period between 10 thousand and 500 years and 7 thousand and 300 years ago, and the reasons for this migration were not known.

Satellite image of fossilized rivers in the border area between Egypt and Sudan (Abdullah Zaki)

To the site of Lake Nasser

According to the study, which was published in the Quaternary Science Reviews, the reason for this migration was an intense rise in the amounts and rates of rain, which led to large floods from the Nile River and the creation of wide swamps, forcing the residents of its valley to migrate.

To reach these results, this team resorted to the border area between Egypt and Sudan (Lake Nasser), and the researchers were interested in studying 6 of the fossilized rivers located there, which are traces of rivers that used to flow in these areas, and then dried up at some time for one reason or another.

Zaki says in his statement to Al Jazeera Net, "For a start, it was necessary to confirm that the water - which was flowing in these rivers during the time period - is of interest to us."

To reach these results, the team used two techniques to date some of the remaining sediments in these rivers, which were flowing with the water, and they are radiocarbon dating and fluorescence dating, both of which indicated that the water actually took place in these areas between 15,000 and 5,000 years ago. This means that migration occurred and the waters flow in these rivers.

From left to right, the sites where people lived before the heavy rain, then migrated during it, and then returned (Abdullah Zaki)

abnormal rates

According to the study, the team then resorted to calculating the amount of water that passes through a specific section of each of those rivers in a specific period of time, which can indicate the amount of rain falling on those areas.

And "to reach these results, we measured the size and thickness of a number of rocky sediments that we obtained from those rivers, which gives us an impression of the rate of rain that moved these sediments inside the rivers in the past," Zaki says in his statement to Al Jazeera Net.

The calculations showed that the rainfall rates in that period were between 55 and 80 millimeters per hour, in addition to that, the researchers extracted the annual rates of rain in those areas and actually found that it was greater than usual before and after this period by 3 to 4 times.

The area we know now as the Sahara was more rainy than at present (Abdullah Zaki)

Climate immigrants

Zaki told Al Jazeera Net, "This was during the so-called African Wet Era, when the region that we know now as the Sahara was more exposed to rain than at present," and the reason for this change in the climate of that region was related to periodic changes that occur every several tens of thousands of years in Earth's orbit.

Meanwhile, over a period of about 3 thousand years, the surrounding areas of the Nile Valley were inhospitable to people, so they abandoned it, and then the rates of rain decreased little by little, and people returned to live near the Nile River again.

"Our study indicates the nature of the relationship between man and the environment around him, which undoubtedly prompts us to reflect on the current problem of global warming," Zaki says at the conclusion of his conversation with Al Jazeera Net, adding that despite the different environmental circumstances, these changes remain with a great impact on humans.

What Zaki says is already observed, and currently global warming is causing millions of citizens to leave their homes, due to lack of water or damage to plants due to high temperatures or floods, so that specialists in these areas now have a term to express this phenomenon, which is the term “climate migrants.” ".