Sudan's former southern rebel leader John Garang has challenged the north to say why the country should stay united.
The peace deal will end more than 20 years of conflict
Mr Garang told reporters in his interim capital, Rumbek, that northerners would now have to accept the southern Sudanese as their equals.
Southerners have been given a large degree of autonomy as part of the peace deal that ended 21 years of civil war.
They are scheduled to hold a referendum in six years to decide whether they want to seek full independence.
Mr Garang was speaking a day after returning to his base for the first time since signing the historic peace deal earlier this month.
He led southern rebels against the government in Khartoum in a bloody civil war until the peace agreement was signed in Kenya.
His organisation, the Sudan People's Liberation Movement (SPLM), is expected to formally ratify the deal.
It will then begin the task of putting together a new southern government.
The peace agreement is designed to end two decades of war between the Muslim north and the mainly Christian south of the country that left an estimated 1.5 million people dead.
As part of the deal, Mr Garang will become vice-president in the central government and will lead an autonomous government in the south from Rumbek.
Sudan's southern rebels have always maintained that their goal is not the creation of a separate southern state but a united country free from discrimination.
Garang returned to Rumbek on Saturday to a hero's welcome
But with a government being assembled and a new flag and national anthem in the offing, southern Sudan has begun to look increasingly like a country-in-waiting, says the BBC's Jonah Fisher in Rumbek.
Mr Garang stressed that it was not up to him as to whether Sudan would remain united.
"The challenge is on the north," he told a news conference.
"You can't be calling for unity [while] asking me to be your inferior," he said.
Rumbek itself has no paved roads or multi-storey buildings and hardly any running water or electricity.
As residents of one of the poorest areas in the world, the southern Sudanese will be looking closely to see whether the long-awaited peace brings opportunity and development, our correspondent says.
If after six years things still have not improved, a vote to separate is a near certainty, he says.
Under the terms of the peace deal, the government of southern Sudan will share oil revenue equally with the government in the north. Hundreds of millions and perhaps even billions of dollars will flow to Mr Garang's new administration.
The Dutch Development Minister, Agnes van Ardenne, visited Rumbek on Friday, promising $130m in European aid - but made it conditional on an end to the continuing conflict in the western region of Darfur.
The UN is hoping to deploy in March some 10,000 international peacekeepers to monitor the agreement, between the Islamic government in the north and Christian and Animist rebels.
But UN sources say the deployment could be delayed by a dispute over which countries will provide the troops.
The SPLM is reported to believe that too many Muslim countries have been asked to contribute.