The Bahr el Ghazal (Arabic: Gazelle River) is both a river and a region of southwestern Sudan, the region taking its name from the river. The river flows about 805 km (500 miles) east to Lake No , where it joins the Bahr el Jebel to form the White Nile (Bahr el Abiad). The region consists of the states of North Bahr al Ghazal, West Bahr al Ghazal, and Lakes. It borders Uganda to the south.

The eponymous region is an area of swamps and ironstone plateaus inhabited mainly by the Dinka people, who make their living through subsistence farming and cattle herding. It was historically subject to raids by the Fur and Arab slave traders from the neighboring region of Darfur. The slave trade was suppressed in 1864 by the khedive of Egypt but soon re-emerged under powerful native merchants, who set themselves up as princes complete with armies. The most powerful of them, al-Zubayr, fought and defeated a joint Turkish/Egyptian force sent to Bahr el Ghazal in 1873. The khedive conceded defeat and made Bahr el Ghazal a nominal province of Egypt, with al-Zubayr as its governor. The region was later incorporated into Anglo-Egyptian Sudan and became the ninth province after being split from Equatoria in 1948, and later a province, and then state, under the Republic of Sudan. In 1996, the region was divided into the three current districts as part of an administrative reorganisation of the country.

The region has been affected by civil war for many years. It was a scene of fighting in the First Sudanese Civil War. In 1982, the Sudan People's Liberation Army (SPLA) was formed there by John Garang to fight the Arab-dominated government in Khartoum. This was the beginning of what quickly became known as the Second Sudanese Civil War. The subsequent conflict lasted until 2003 and killed more than two million people. A substantial fraction of the population of the region is internally displaced or refugees in neighboring countries.