The Dinka and Nuer, two rival pastoralist groups, have competed over grazing land and water for their cattle in the past. These clashes have usually taken place in a local context without causing massive amounts of fatalities. However, in 2013, the dismissal of the former vice president Riek Machar, a Nuer, by the South Sudanese president Salva Kiir, a Dinka, functioned as a catalyst for mass violence, claiming more than thousand victims.