Darfur is a Sudanese region where fighting between African rebel groups and the Janjaweed (aided by Sudan) is ongoing. This region has historically been ripped apart between Arab nomads and more sedentary African groups. Since Sudan's independence in 1956, tensions have never ceased to increase.
The Sudanese government is and has always been majoritarily composed of arabs, and black africans from the south of Sudan and Darfur have often complained of being 'dominated and oppressed by the Arabs'. It is in this tense situation that the Sudan Liberation Front (SLA) and Justice and Equality Movement (JEM), armed groups that prône the independence of an 'African' Sudan or Darfur, were created. These groups have invaded towns of Darfur asking for a better distribution of resorces.
The answer of the central Sudanese government led by Omar al-Bashir (1993-2019) was judged 'brutal'. Sudanese forces and the arab Janjaweed militias (aided by Sudan) attacked the rebels' positions, with heavy civilian casualties. The conflict spread all the way to the south of Sudan, where the South Sudan People's Defence Forces (SSPDF), closely linked to the SLA, was formed. That is why the African Union and the UN decided, in 2007, to send the UNAMID mission to reestablish peace, unsucsessfully. This conflict ended in 2011 with the independence of South Sudan.