Sudan's government and southern rebels have signed a comprehensive peace deal to end Africa's longest civil war.
The peace accord brings new hope for Sudanese people
Foreign dignitaries including US Secretary of State Colin Powell were among those attending the ceremony in the Kenyan capital Nairobi.
The war, which began over 20 years ago, has pitted the Muslim north against Christians and animists in the south, leaving some 1.5m people dead.
The peace deal does not cover the separate, newer conflict in Darfur.
The peace deal "will close a dark chapter in the history of
Sudan ... This is a promising day for the people of Sudan, but only if today's promises are kept," Mr Powell said.
Sudanese president Omar el-Bashir said: "Our people have experienced the bitterness of war ... Peace is indeed going to bring our country abundance."
He also promised to bring an end to the worsening humanitarian crisis in Sudan's Darfur province.
"We are going to work together with our peace partners
... to ensure peace prevails in every part of the country,"
United Nations Secretary General Kofi Annan has warned of worsening violence in Darfur, western Sudan, where government-backed militia are accused of killing thousands as part of a campaign against rebels demanding more rights.
On the eve of the signing, Mr Powell said the end of the north-south civil war should spur on efforts to find a solution to the crisis.
And the main southern rebel leader, John Garang, said he hoped to be involved in peace talks on Darfur once he joined the planned national unity government.
FINAL PEACE DEAL
Both sides will unify into 39,000-strong force if the south does not secede after six years
The south will have autonomy for six years followed by referendum for secession
To be shared 50:50
To be split 70:30 in favour of the government in the central administration
To be split 55:45 in favour of the government in Abyei, Blue Nile State and the Nuba mountains
To remain in the north
Sharia in Khartoum to be decided by elected assembly
Mr Garang, who is set to become a vice-president, signed the peace deal on behalf of the leader of the Sudan People's Liberation Army (SPLA).
The government side was represented by Vice-President Ali Osman Taha.
The Kenyan government was so delighted by the success of the long, tough negotiations that it threw the event open to ordinary people.
Thousands attended, and the deal was marked by singing, dancing and cheering by exiled Sudanese.
There will be celebrations not just in Sudan but across the region and among the Sudanese diaspora around the world.
Starting in July, the south will be autonomous for six years and will then vote in a referendum to decide whether to remain part of Sudan, or become independent.
Sudan's new oil wealth - currently producing about 320,000 barrels a day - is to be split equally between north and south.
Apart from an 11-year period from 1972-1983, southern Sudan has been at war continuously since 1956. Peace talks began in 2002.
In 1983, the government - dominated by northern Arabs - tried to impose Islamic Sharia law across Sudan, even in areas where the majority is not Muslim.
The peace deal signed in Nairobi follows the signing of a permanent ceasefire on New Year's Eve.