The Khabur River is the largest perennial tributary to the Euphrates in Syria. Although the Khabur originates in Turkey, the karstic springs around Ras al-Ayn are the river's main source of water. Several important wadis join the Khabur north of Al-Hasakah, together creating what is known as the Khabur Triangle, or Upper Khabur area. From north to south, annual rainfall in the Khabur basin decreases from over 400 mm to less than 200 mm. This has made the river a vital water source for agriculture throughout history. The Khabur joins the Euphrates near the town of Busayrah.

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. Originating in Turkey, the Euphrates flows through Syria and Iraq to join the Tigris in the Shatt al-Arab in Iraq, which empties into the Persian Gulf.