The Balikh River () is a perennial river that originates in the spring of Ain al-Arous near Tell Abyad in the Eastern Mediterranean conifer-sclerophyllous-broadleaf forests ecoregion. It flows due south and joins the Euphrates at the modern city of Raqqa. The Balikh is the second largest tributary to the Euphrates in Syria, after the Khabur River. It is an important source of water and large sections have recently been subjected to canalization. Geography The primary source of the Balikh River is the karstic spring of Ain al-Arous, just south of the Syria–Turkey border. Additionally, the Balikh receives water from a number of periodical streams and wadis that drain the Harran Plain to the north, as well as the plains to the west and east of the river valley. These streams are the Jullab, the Wadi Qaramogh, and the Wadi al-Kheder. A few kilometres south of Ain al-Arous, the Balikh is joined by the channel of the Jullab. This small river rises from springs north of Şanlıurfa, but already runs dry at Harran, before it can reach the Balikh. Numerous now dried-up wells in the old city of Harran suggest, however, that the water table may have been significantly higher in the past. The Wadi al-Kheder drains the plain to the east of the Balikh Valley, and is fed by the Wadi al-Burj and the Wadi al-Hamar, which in turn is fed by the Wadi Chuera. These wadis, as well as the Wadi Qaramogh, can transport considerable amounts of water after heavy rainfall, and large limestone blocks can be found in their lower courses. History The Balikh river forms the heart of a rich cultural region. On both banks are numerous settlement mounds dating back in some cases to at least the Late Neolithic, the 6th millennium BCE. In the Bronze Age (3rd millennium BCE) ancient Tuttul (close to present-day Raqqa at the delta of the Balikh) and Tell Chuera in the north (in the Wadi Hamad close to the Balikh) were important cities. Over the millennia the region saw ongoing interaction between nomadic tribes and settled populations. One sometimes got the upper hand over the other. In classical Antiquity the region was called Osrhoene with the capital at Edessa/Callirrhoe (ar-Ruha'.) Ar-Ruha' and another prominent ancient town of the Balikh valley, Harran (Roman Carrhae), figure in the Muslim and Jewish traditions respectively in the stories of Abraham and other Hebrew patriarchs