A Vietnamese court has sentenced six ethnic minority Montagnards to between seven and 17 years jail for "threatening national security".
The men, from the Central Highlands, were found guilty of inciting protests in 2004 to call for religious freedom, the Vietnam News Agency reported.
The men face an additional five years' surveillance after their release, the agency said.
Vietnam has been criticised by rights groups for repressing the Montagnards.
Many are Protestants who follow an evangelical Christian Church not sanctioned by the government. They claim their tribal lands have been taken to grow cash crops and that they face constant harassment from the police.
The 2004 protests, which centred on the capitals of Dak Lak and Gia Lai provinces, were quickly suppressed by security forces.
The crackdown led to hundreds of Montagnards fleeing across the border to Cambodia, from where many have been resettled in places like the US and Finland.
Correspondents say the communist government in Vietnam officially guarantees religious freedoms, but both majority Buddhists and minority Christians have complained of violations to their right to worship.