Why was their conflict between northern and southern sudan

First war:
Sudan’s first civil war was fought between the Arab-led Khartoum government in the north and rebels in the largely Christian and animist south. Southern rebels were fighting for regional autonomy and representation in the government.
After a succession of governments, that were never able to address the problems of factionalism, economic stagnation, and ethnic division, a group of communist and socialist officers led by Colonel Gaafar al-Nimeiry took over power in a coup in 1969. Nimeiry made attempts to bring factions within Sudan together, including the southern Sudanese. A peace agreement was signed in 1972 that granted semi-autonomy to the south.

Second war:
Facing pressure from Islamists in Sudan, in 1983 President Nimeiry made the decision to abolish the south’s semi-autonomous government, consolidate power in Khartoum, declare Arabic the official language, and institute Sharia law throughout the country (even the primarily Christian and animist south). In response, Dr. John Garang de Mabior, a career soldier and economist trained and educated in the United States, headed the rebel movement known as the Sudan People’s Liberation Army/Movement (SPLA/M) in an uprising against Khartoum, kicking off the Second Sudanese Civil War. The grievances of the second civil war were similar to the first, and the SPLA/M was fighting against the Islamic state, Islamic law, and centralized power that Nimeiry instituted. Garang believed in a united Sudan without the stark ethnic factional divides that had plagued the country for decades. Nimeiry was ousted from power in 1985, but the war continued. In 1989, Colonel Omar al-Bashir led a group of army officers in a bloodless military coup. Over the years, under Bashir’s leadership he ruled by repression, expanded the influence of Islam in government, and supported radical Islamic groups throughout the region. Khartoum hosted and provided a safe haven to a number of radicals and radical groups, including Osama Bin Laden’s al Qaeda. In 1993, Bashir appointed himself President of Sudan, a position he has held ever since. Three years later, Bashir established the ruling National Congress Party (NCP) and created a single-party totalitarian state. Throughout this time, until the early 2000s, Khartoum committed crimes against humanity, war crimes, and potentially even genocidal attacks on civilian populations in southern Sudan. The government conducted a widespread ‘scorched-earth campaign’–destroying crops, homes, and killing livestock–using food as a weapon of war, in addition to aerial bombardments and military/militia attacks from the ground.