Anyanya also Anya-Nya were a southern Sudanese separatist rebel army formed during the First Sudanese Civil War (a civil war sometimes referred to as Anyanya I) which started in 1955. A separate movement that rose during the Second Sudanese Civil War were, in turn, called Anyanya II. Anyanya means "snake venom" in the Madi language.
From about 1969, the Nuer, Lotuko, Madi, Bari, Acholi, Zande, Dinka, and other people from the entire southern region of Sudan waged a war against the Sudanese government. This mobilization came to be known as the Anyanya rebellion or the First Sudanese Civil War. It ended when the Anyanya signed the Addis Ababa Agreement with the Government in 1972.
In 1978, Nuer dissidents calling themselves Anyanya II took up arms in eastern Upper Nile. When the Addis Ababa Agreement fell apart in 1983, marking the beginning of the Second Sudanese Civil War, the Sudan People's Liberation Movement/Army (SPLM/A) was founded. Competition between Anyanya II and the SPLM/A led to the defeat of Anyanya II. Some of its members were incorporated into the ranks of the SPLM/A, and others were consolidated into a militia supported by the government of Sudan.Those who did not join either came to form, along with tribal militias that emerged in response to the lawlessness of some SPLM/A units, the South Sudan Defence Forces.