Most of Darfur's rebel groups have agreed on a common position and want "final" talks with Sudan's government within two or three months.
Mediators and rebel leaders expressed optimism
The eight factions have been in talks since Friday to end their divisions - seen as a major factor in the failure to end the four-year conflict.
However, one of the key rebel leaders boycotted the meeting in Tanzania.
The agreement follows last week's decision to send 26,000 UN and African Union peacekeepers to Darfur.
The factions had reached a "common platform on power-sharing, wealth-sharing, security arrangements, land and humanitarian issues, for the final negotiations", they said in a statement.
BBC East Africa correspondent Karen Allen says details of the platforms are being presented in a confidential document, which will now be taken to Khartoum to set an agenda for revived peace talks.
Special UN envoy to Darfur Jan Eliasson told the BBC the agreement was an important step forward.
"One of the main problems we have had to reach negotiations has been the split and the splintering among the rebel movement," he said, adding that he was on his way to the Sudanese capital, Khartoum, for discussions with the government.
International Crisis Group analyst Hannah Stogdon told Reuters news agency that it depended on who would represent the rebels in talks with the government.
"If they can agree on that publicly, that is a good sign."
Rebel leader Ahmed Hussein said the deal would "pave the way for a meaningful and positive new political process to solve the root causes of the conflict in Darfur".
The talks in Arusha were due to end on Sunday but were extended by a day.
One of the key rebel leaders, Abdul Wahid Mohammad Ahmed al-Nur, of the major faction of the Sudan Liberation Movement, boycotted the talks, saying a ceasefire should be agreed before political talks.
The African Union special envoy to Darfur, Salim Ahmed Salim, told the BBC that Mr Nur should take the current opportunity to put aside his differences and join the peace process.
"We are now at the pre-negotiation level, and we hope that the negotiations will begin within the period of two months."
KEY REBEL PLAYERS
SLM: Minni Minnawi's faction signed 2006 peace deal
SLM: Abdul Wahid Mohammad Ahmed al-Nur's faction rejected peace deal
Jem: Khalil Ibrahim, one of the first rebel groups, rejected deal
Rebel negotiator: Suleiman Jamous
SLM Unity: Abdallah Yehia
UFLD: recently formed umbrella group including SLM commanders
Other breakaway SLM commanders: Mahjoub Hussein, Jar el-Neby and Suleiman Marajan
There are estimated to be more than 13 rebel factions in Darfur
"It is not seen as logical to have the government of Sudan negotiating with 10 or 15 difference factions, so we have encouraged all the participants at the Arusha meeting to... find a minimum common denominator among themselves," he said.
At least 200,000 people are believed to have died and more than two million have been left homeless since 2003.
Sudan's government and pro-government Arab Janjaweed militias are accused of war crimes against the region's black African population, although the UN has stopped short of calling it genocide.
The talks follow last week's UN Security Council resolution to send 26,000 peacekeepers to Darfur.
Though the fighters in Arusha have welcomed the announcement that more peacekeepers will be deployed, they know that a political solution is the only way forward, says BBC Africa analyst David Bamford.
After months of wrangling, Sudan agreed to the UN resolution after it was watered down.