The Arabs who named it Bahr al-Arab called it the Sea of the Arabs, though it is not a sea and is not particularly large. The Dinka who have lived along its southern bank for far longer simply call it the Kiir. The river flows east for roughly eight hundred kilometres through southwestern Sudan, tracing in places the international border between Sudan and South Sudan, before it feeds the Bahr el Ghazal system that in turn feeds the White Nile. The Kiir has always been a boundary. For as long as Dinka and Baggara oral traditions reach, it has been a line along which cattle-keepers from two cultures have met, traded, married, and fought.
The Bahr al-Arab - probably a contraction of Nahr al-Arab, meaning River of the Arabs - marks the historical frontier between the Arabic-speaking Baggara, cattle-herding Muslims of southern Kurdufan and Darfur, and the Nilotic Dinka, cattle-herding Christians and traditionalists of the Bahr el Ghazal. These are not merely neighbours. They are parallel cultures built around the same foundation - cattle - and the same landscape - flooding plains of sorghum and grass - and they have been sharing, competing for, and quarrelling over the same grazing for centuries. The river itself is the negotiated edge of that coexistence.
The Bahr al-Arab rises in tributaries draining the Bongo Massif and the Marrah Mountains in Darfur, close to Sudan's borders with Chad and the Central African Republic. The Adda and Umbelasha flow east from the Bongo; the Ibrah flows south from Marrah. These streams combine to form the Bahr al-Arab, which then runs east along the Darfur-Bahr el Ghazal boundary and across southern Kurdufan. The Lol River joins it from the south. The Jur joins it soon after - or, depending on which sources you trust, joins the Bahr el Ghazal just before it does. The Bahr el Ghazal then flows a short distance east to meet the White Nile in the Sudd wetlands. Despite having the largest drainage basin of any Bahr el Ghazal tributary, the Kiir carries very little water compared to the rivers to the south, and it flows sluggishly. The land around it is thirstier than the land it drains.
During the Second Sudanese Civil War, the Bahr al-Arab's position on the north-south frontier made it a military front. Droughts and crop failures in the early 1980s pushed various peoples of western Sudan southward. The Baggara moved south of the Bahr al-Arab into Dinka grazing lands, and the resulting competition for resources turned into violence. The Sudanese military backed the Baggara, arming and organising militias known as murahileen to fight the Sudan People's Liberation Army. Through the 1980s the murahileen raided south, targeting Dinka cattle camps, Dinka villages, and Dinka people - who were captured, killed, or driven from their homes. By the end of the decade the land along the Bahr al-Arab was devastated and the population, in the plain language of the Wikipedia entry, decimated. The word understates what happened to Dinka families whose children vanished into servitude in the north.
In the rainy season the Bahr al-Arab rises, floods its banks, and spreads into seasonal marshland. In the dry season it retreats to a sluggish thread of water in a wide sandy bed, punctuated by pools where fish concentrate and where cattle come to drink. The Nile system it feeds is, farther south, a river of enormous power. The Bahr al-Arab is something quieter - a river shaped more by the rhythms of drought and flood than by volume. That quiet is deceptive. This is a river that has mattered, politically and demographically, out of all proportion to its flow. Where it runs, peoples meet. Where peoples meet, borders emerge. Where borders emerge, the map-makers in Khartoum and Juba argue over lines the cattle pay no attention to.
The disputed region of Abyei, at the centre of the tensions between Sudan and South Sudan since the 2005 Comprehensive Peace Agreement, sits right on the Bahr al-Arab's path. The Ngok Dinka have lived along the river here for generations. The Misseriya Baggara have grazed their cattle here in the dry season equally long. Who controls Abyei - and therefore the Bahr al-Arab crossings - remains unresolved. A 2011 referendum was postponed; the Sudanese Armed Forces occupied Abyei town; a UN peacekeeping force has been deployed since. The river runs on. The cattle keepers on both sides wait for negotiations that never quite arrive.
The Bahr al-Arab flows roughly east-west through southwestern Sudan and along parts of the South Sudan border, with its approximate midpoint at 9.03 degrees N, 29.47 degrees E. From altitude the river is most visible in the wet season (June-October) when it swells and floods its basin; in the dry season it retreats to a narrow thread in a wide sandy bed. The nearest major airfields are El Obeid (ICAO HSOB) in Sudan and Wau (HSWW) in South Sudan. The Abyei region, through which the river passes, remains contested between Sudan and South Sudan and should be treated as sensitive airspace.