Leaders of the Free Aceh Movement (GAM), fighting for the region's independence for three decades, and Indonesian officials held talks for the first time in two years in Helsinki, Finland, on Friday.
United in grief, both sides discussed how to work together to rebuild after the 26 December disaster in which at least 100,000 Acehnese died or went missing.
Malik Mahmud, prime minister of GAM's government-in-exile, which has been based in Stockholm since the struggle began in 1976, said he was pleased by the talks.
"Everything is going good. At the moment I cannot reveal the content. I am happy," he said after 12 hours of talks.
The Indonesian side declined to comment. But sources said the talks dealt with the humanitarian crisis.
Indonesian President Susilo Bambang Yudhoyono said this week that Jakarta was offering special autonomy status to Aceh, something GAM had previously rejected.
GAM insists on independence for the gas-rich region on the northern tip of the Sumatra island.
The conflict turned bloodier in May 2003 after peace talks collapsed. More than 12,000 people have been killed in the violence.
But since the tsunami struck, devastating Aceh more than any other spot in the Indian Ocean, both sides have made ceasefire offers.
Susilo has spoken of the "great momentum" toward ending the conflict and uniting the two sides "as brothers to further rebuild Aceh after being hit by the tsunami".