The 'ndrangheta organized crime network took over from the Cosa Nostra as the wealthiest and most powerful Italian Mafia in the world. Another 355 people will be tried and face sentencing in coming years.
The Italian justice system has prepared a specially adapted courtroom to judge defendants in the "maxi trial" of alleged mobsters that operated in the Calabria region on the "toe" of the Italian mainland.
Judges handed six of those convicted at Saturday's trials the maximum 20-year sentence asked for by prosecutors. They included Pasquale Gallone, 62, the right-hand man of alleged 'ndrangheta boss Luigi Mancuso and Gregorio Niglia, who was convicted of buying weapons and extortion.
They acquitted 21 of the accused, seven at the request of prosecutors, according to famed anti-Mafia prosecutor Nicola Gratteri.
Gratteri, who has lived under police escort for the last 30 years for his efforts to lock up the 'ndrangheta, said the sentencing had gone "very well."
"Out of 91 defendants, there were 70 presumed innocent who were convicted," Gratteri told Italian news agency AdnKronos, adding those acquitted were minor offenders.
How important are these convictions?
The 'ndrangheta rose to prominence as the most powerful Mafia in the world after another "maxi trial" in the late 1980s dealt a heavy blow to Sicily's Cosa Nostra.
Experts believe 150 families are part of the organization, supported by 6,000 members and affiliates in its base of operations in Calabria. Thousands more are believed to work for the 'ndrangheta worldwide.
Their international reach allows them to reinvest in the legal business ventures mainly in Calabria.
Italy's largest mafia trial to begin
Prosecutors charged many of the suspects with attempted murder, money laundering, usury, drug-dealing, extortionand illegal weapons possession.
Alleged 'ndrangheta boss 'The Uncle' Mancuso, 67, and ex-senator Giancarlo Pittelli, 68, who prosecutors believe was his fixer, will face longer court cases over coming years.