Badri Hartono led an extremist group called Al-Qaeda Indonesia and was found guilty of sending recruits to a militant camp on a jungle-clad island known as a terror hotbed.
Hartono also provided shelter in 2009 to terror leader Noordin Mohammed Top, head of a violent splinter faction of the radical Jemaah Islamiyah network that carried out attacks on Western targets, prosecutors said.
Hartono "recruited and sent people to Poso," judge Musa Arif Aini told the Jakarta court, referring to an area on Sulawesi island where militant training camps are based.
His group had also planned attacks on security forces, according to prosecutors.
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Analysts said it was not clear whether Hartono's group was linked to the real Al-Qaeda, but many groups have copied the name of the terror outfit founded by Osama bin Laden.
Noordin, the self-proclaimed leader of "Al-Qaeda in the Malay Archipelago", was accused of masterminding attacks on Jakarta's Marriott hotel that killed 12 people in 2003, as well as the 2005 bombings on Bali that killed 20.
After a long and bloody hunt, he was finally killed in a raid outside Solo city in Central Java province in September 2009.
Indonesia, which has the world's biggest Muslim population, has waged a crackdown on militant groups over the past decade since a string of terror attacks on Western targets.
The crackdown has been credited with weakening key networks.