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.

Julian was the Caesar of the West from 355 to 360 and Roman emperor from 361 to 363, as well as a notable philosopher and author in Greek. His rejection of Christianity, and his promotion of Neoplatonic Hellenism in its place, caused him to be remembered as Julian the Apostate in Christian tradition. He is sometimes referred to as Julian the Philosopher.