The Intermediate People's Court of Lhasa announced the sentences at an open session, the official Xinhua News Agency reported. It gave no other immediate details.
China's state broadcaster reported that 200 people attended the trial, the first since the mid-March riots.
The protests, initially led by Buddhist monks, started peacefully on March 10, the anniversary of a failed Tibetan uprising against Chinese rule. They became violent four days later as Tibetans attacked cars and shops runs by Han Chinese, China's majority ethnic group.