How many countries does the Euphrates river flow through?

The Euphrates is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia (the "Land between the Rivers"). Originating in eastern Turkey, the Euphrates flows through Syria and Iraq to join the Tigris in the Shatt al-Arab, which empties into the Arabian Gulf.

The Euphrates receives most of its water in the form of rainfall and melting snow, resulting in peak volumes during the months April through May. Discharge in these two months accounts for 36 percent of the total annual discharge of the Euphrates, or even 60–70 percent according to one source, while low runoff occurs in summer and autumn.

In Syria, three rivers add their water to the Euphrates; the Sajur, the Balikh and the Khabur. These rivers rise in the foothills of the Taurus Mountains along the Syro–Turkish border and add comparatively little water to the Euphrates.

Throughout history, the Euphrates has been of vital importance to those living along its course. With the construction of large hydropower stations, irrigation schemes, and pipelines capable of transporting water over large distances, many more people now depend on the river for basic amenities such as electricity and drinking water than in the past.