The Anya Nya (the Madi term for 'snake/scorpion venom') were a group of separatist rebels formed by Joseph Lagu in 1963 as the military wing of the Southern Sudan Resistance Movement (SSRM). The SSRM had been openly acting against the northern dominated Sudanese government since independence in 1956. The Anya Nya fought the First Sudanese Civil War, or Anya Nya Rebellion, from 1963 until 1972, when Lagu and the Sudanese president, Jaafar Muhammad an-Numeiry, signed the Addis Ababa Agreement. The 1972 Addis Ababa Agreement granted Southern Sudan autonomy, creating the Southern Sudan Autonomous Region.
In 1983 civil war sparked up again when an-Numeiry's predominantly Islamist government abandoned the 1972 Agreement. Initially a group calling themselves Anya Nya II fought against government troops. They were soon absorbed into the Sudan People's Liberation Army led by Colonel John Garang.