the sslm was formed in the context of widespread factional fighting among the western nuer ethnic group of unity, south sudan, who had signed a peace treaty with the government on 21 april 1997. the pro-government ssdf militia, comprising a large number of nuer, had divided into warring factions led by riek machar and paulino matip. as riek was being defeated, opposing government-aligned militias attacked civilians around the oilfields in south sudan, causing a stream of nuer refugees to flee towards spla-controlled bahr al-ghazal for protection. at least two previously pro-government nuer militias aligned themselves with the spla, while the few nuer loyal to the politically weakened riek began to abandon the government's cause. the fact that nuer refugees were being protected by the dinka-dominated spla led to an unusual conference in wunlit, sponsored by the new sudan council of churches and the safety of which was guaranteed by the spla. groups of western nuer and dinka from tonj, rumbek and yirol took part, leading to a peace agreement in march 1999 to end the ethnic fighting. the creation of the sslm was accompanied by the announcement that most of the nuer had formally broken away from the government. between november 1999 and january 2000, the group was known as the upper nile provisional military command council (umcc).