Sudan and South Sudan have agreed a framework agreement to give their citizens basic freedoms in both nations, African Union mediators say.
They have agreed to allow citizens of the other state to live, work and own property on either side of the border, and travel between the two nations.
Analysts say deals have been broken in the past, and the two sides have left space to wriggle out of this accord.
Bitter disagreements over disputed land and oil also remain unresolved.
However, officials said Sudanese President Omar al-Bashir would make his first visit to South Sudan since the country gained independence last July.
He is expected to make the trip in the next two weeks.
The framework deal said nationals of each state would be given "freedom of residence, freedom of movement, freedom to undertake economic activity and freedom to acquire and dispose property".
Two months ago, Khartoum had threatened to treat South Sudanese as foreigners from 8 April unless they obtained residency or work permits.
Some 350,000 southerners have moved to South Sudan since October 2010, after decades living in the north, but some 700,000 southerners remain, according to the UN.
The BBC's James Copnall, in Khartoum, says that the accords can, at best, be seen as agreements in principle.
A series of signed deals have not been respected in the past and the talks have yet to lead to a breakthrough in the key issue of oil, our correspondent says.
In January, South Sudan shut down all of its oil fields in a row over the fees Sudan demands to transit the oil.
South Sudan depends on oil sales for 98% of state revenues, but has pledged not to restart production until a deal is reached.
Parts of the countries' common border also remain in dispute.
In February, the two states agreed to demarcate most of the border within three months, although this would exclude five disputed areas.