The sentences -- ranging from 13 to 17 years -- were handed down Friday in the Russian republic of Dagestan.
The defendants were convicted of hatching a scheme to bomb crowded Red Square on New Year's Eve 2012.
The bomb exploded inside two attackers' hotel room two days before it was meant to go off.
Russia's RIA Novosti news agency said the reputed terror ring had also been behind a string of attacks on law enforcement officers and a railway in the North Caucasus.
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