Prabhu Ramamoorthy will be deported to India after serving the sentence. "His life is effectively over," his defense attorney told a judge.
The Guatemalan girl was traveling with a group of 163 people who turned themselves in Dec. 6.
"I’ll take my penalties," said one of the four who had been trapped. "I’ll go along with it. I’ll move along and be a better person for it."
Federal prosecutors next want to seize the Mongols' trademark patch, which is big business for the 600-member "criminal enterprise."
Many of the threats, none of which have been found to be credible, demanded payment in bitcoin, authorities said.