1955 Beginning of first civil war between north and south.
1972 The Addis Ababa Agreement, granting autonomy for the South, ends 17 years of civil war.
1983 War returns. The government, dominated by northern Arabs, adopts aspects of Islamic sharia law and later, martial law. The new law enrages the mostly animist and Christian south.
1983-84 Southern rebels, led by John Garang, organize Sudan People's Liberation Army (SPLA). The resulting 21-year war is fueled by the south's rich oil reserves, ethnic differences, and the south's desire for self governance.
1985 Fighting in southern Sudan escalates to highest levels yet. Khartoum and other towns fill with refugees from the south and west.
1989 Lt. Gen. Omar Hassan al-Bashir takes power in bloodless coup.
1991 Osama bin Laden moves his Al Qaeda organization to Sudan.
1992 Mr. Garang, the SPLA chief, proposes a referendum on southern self-determination. Government forces launch major offensive in response to a failed SPLA invasion of Juba.
1993 Ethiopia, Eritrea, Uganda, and Kenya establish the Intergovernmental Authority on Development (IGAD) to resolve the civil war.
1996 Osama bin Laden is expelled. He goes to Afghanistan.
1997 Khartoum Peace Agreement signed between the government and six splinter rebel groups - but the SPLA remains absent from the table.
2001 Kenyan Gen. Lazaro Sumbeiywo named chief mediator. Former US Sen. John Danforth designated US presidential envoy for peace in the Sudan.
2001-2003 Three years of intense negotiations between SPLA and Khartoum over the future of southern Sudan.
January 2005 SPLA chief Garang and Sudan's lead government negotiator Ali Osman Taha sign a comprehensive peace accord ending a civil war that claimed the lives of more than 2 million. US Secretary of State Colin Powell attends the ceremony.
April 2005 Donors at a conference in Norway pledge $4.5 billion to help southern Sudan recover from the civil war.
July 2005 Garang sheds rebel role, swearing the oath of office as first vice president. President Omar Hassan al-Bashir, who also signed a new interim constitution, takes his own oath of office. Three weeks later, Garang dies in a helicopter crash in southern Sudan. Members of SPLA vow to faithfully implement the peace plan their leader signed.
Sources: Sudanupdate.org; British Broadcasting Corp.