Pressure is mounting on Sudan over Darfur. In January, a long-sought hybrid United Nations and African Union peacekeeping force began working in Darfur, but the Sudanese government’s quibbling over which countries the troops will come from and bureaucratic delays have stalled the force’s deployment.

Sudan’s biggest trading partner and ally, China, has also come under pressure from advocates who have linked the Olympic Games in Beijing this summer to the fighting in Darfur. China has been more publicly critical of the Sudanese government in recent weeks. Sudan has also been trying to improve its relationship with the United States, and last week, President Bush’s new special envoy to Sudan, Richard S. Williamson, visited Darfur and the Sudanese capital, Khartoum, meeting with President Omar al-Bashir. Any improvement in relations, he said, would be contingent on tangible improvements in the humanitarian situation.

“Since the first of the year another 75,000 people in Darfur have been displaced,” Mr. Williamson said in a telephone interview. “That is more than a thousand a day. There are not going to be any changes until that reverses.”

Image International aid organizations distributed food and cooking oil last week in Suleia, Sudan, after attacks by government forces and Arab militias. Credit... Lynsey Addario for The New York Times

Origins of a Conflict

Despite the pressure, the government seems determined to fight on, and the most powerful rebel groups  the biggest factions of the Justice and Equality Movement and the Sudanese Liberation Army  have refused to sit down for talks. So the violence continues, tracing a familiar arc as it wears on.

It was five years ago last week that an attack by rebels from non-Arab tribes like the Fur, Masalit and Zaghawa, seeking greater wealth and autonomy for the neglected and impoverished region of Darfur, prompted the Arab-dominated government to marshal Arab militias in the region that ultimately evicted millions from their homes, burning, looting and raping along the way. The campaign effectively pushed many non-Arab people off their land and into vast, squalid camps across Darfur and Chad.

In the first two years of the conflict, 2003 and 2004, joint attacks by the Sudanese Army, janjaweed militiamen and the government’s old Russian-made Antonov bombers terrorized Darfur, waging a brutal counterinsurgency against non-Arab rebel groups by attacking their fellow tribesmen in their villages. At least 200,000 are believed to have died as a result of the violence or sickness and hunger caused by the crisis, according to international estimates, with the majority of violent deaths in that period.