Ancient Waterways Merged to Form the Euphrates River 1.6 Million Years Ago

A new study reveals that the Euphrates River—a lifeline of ancient civilizations—was born from the merger of two massive waterways, each larger than the modern Nile.

A study published in Nature Geoscience on June 1, 2026, reports that the Euphrates River originated from the merger of two ancient waterways approximately 1.6 million years ago. The research, conducted by lead author Andrew Madof—a senior seismic stratigrapher at Chevron—and colleagues, used seismic data, land surface maps, and satellite imagery.

Formation Timeline

According to the study, the Paleo-Karasu and Paleo-Murat rivers originally discharged into the eastern Mediterranean Sea beginning around 5.4 million years ago. The Mediterranean partially dried up during the Messinian salinity crisis (5.96 to 5.33 million years ago) and refilled 5.33 million years ago, submerging river deposits offshore present-day Lebanon and Turkey.

Tectonic shifts caused the Paleo-Murat river to change course around 3.6 million years ago. The Paleo-Karasu river followed approximately 800,000 years later, at around 2.8 million years ago.

By about 1.6 million years ago, both rivers had merged and flowed southeast into the Persian Gulf, forming the modern Euphrates River.

Each of these ancient rivers, prior to merging, was larger than the modern Nile River.

Significance and Context

Madof noted that the findings clarify the river's origins, which had previously been uncertain. Earlier hypotheses included a single river flowing into the Mediterranean, a river ending on the Arabian Peninsula, or a river flowing into ancient lakes in Turkey.

The Euphrates River is a key water source in the Fertile Crescent, a region in Western Asia that includes Mesopotamia. The Tigris and Euphrates rivers created fertile soil that supported ancient civilizations such as the Sumerians and Assyrians approximately 6,000 years ago.

Madof stated that the merger of the two ancient rivers likely influenced the formation of the Fertile Crescent, and that understanding the Euphrates' formation helps explain how changes in water distribution reshape landscapes.

Implications for Human Migration

The research suggests that changes in river position likely affected mammal migration routes out of Africa through the Levant by altering water availability.

The study is published under DOI: 10.1038/s41561-026-01962-x.