Since gaining independence from Britain in 1956, Sudan’s ruling class has justified its power with an ideology that favors the Arabic-speaking and Arabized elite in the capital Khartoum over populations from the nation's more culturally, religiously, and linguistically diverse regions living on the periphery. While often described as a country split along a north-south axis, because that has long been a fault line of conflict, the concentration of power and wealth is divided between the center and peripheries.
For most of the twentieth century, British colonial rulers treated the north and south as two separate entities. The first Sudanese civil war (1955-1972) erupted just before independence was granted, prompted by angry southerners who had been promised and then denied regional autonomy. The fighting resulted in the death of half a million people, mostly civilians, and forced hundreds of thousands to flee from their homes. In 1972, the Addis Ababa Agreement negotiated peace between the southern rebels, known as the Anyanya, and Khartoum. The peace deal included power-sharing agreements, security guarantees, and political and economic autonomy for the South.
In an attempt to quiet critics in the north and consolidate his power, then-Sudanese President Jaafar al-Nimieri introduced new legal measures in 1983 that abolished southern governing autonomy. Nimieri returned power to Khartoum, declared Arabic the official language, and imposed Sharia law over the entire country. In response, southerners mobilized around the southern rebel army, the Sudanese People's Liberation Army (SPLA), led by Dr. John Garang. Rather than fight for southern independence, the SPLA posited that Sudan needed to be transformed into a multi-racial, multi-lingual, multi-religious, and multi-ethnic state.
In the north, Islamists gained political strength and on June 30, 1989, Brigadier-General Omar Hassan Ahmad al-Bashir led a military coup, bringing to power the National Islamic Front (NIF). The NIF intensified the war with the South, conducting the fighting with systematic and widespread assaults against civilians.
The war continued until 2005, when a Comprehensive Peace Agreement was signed in Abuja, Nigeria, between Garang and Bashir. As part of that peace agreement, citizens of the south were given the opportunity for a future vote on whether to remain part of Sudan or to break off and become an independent country. This vote was held in January 2011, and the citizens of South Sudan voted overwhelmingly for independence. On July 9, 2011, the Republic of South Sudan was born.
When the western region of Darfur experienced increasingly violent internal disputes over access to land and power in the 1990s, the Sudanese government responded by rewarding and arming local leaders who shared its ideology. Fighting began in Darfur when members of the Fur, Zaghawa, and Masalit ethnic groups created the Sudan Liberation Army (SLA) and attacked a government airfield on April 25, 2003. Another rebel group, the Justice and Equality Movement (JEM), joined the fight against the Sudanese government forces.
In response to the April 2003 rebel attack, the Sudanese government began recruiting local militias and transforming them into semi-regularized forces known as the Janjaweed. A period of intensive, systematic targeting of the civilian populations from the Fur, Zaghawa, and Masalit ethnic groups resulted in the deaths of at least 200,000 people between 2003 and 2005 alone. More than two million people—a third of the population—were displaced.