The four Pakistani nationals have been identified as Khuda Balouch Buksh (47), Sikander Ali Teepu (29), Haroon Ahmad Tanooli (31) and Mustajab Ali Raza (28). The fifth Saaim Aslam (31), an American, has been sentenced to 12 months.
All of them had pleaded guilty to the charges.
Two of them Buksh and Raza have been ordered to be deported following the completion of their prison term.
A federal indictment was returned by a grand jury on April 12, 2012 charging federal drug trafficking violations.
"Enforcement entities nationwide are aggressively pursuing prosecutions of any individuals who attempt to import and distribute these adulterated, misbranded, and counterfeit controlled substances," said Daniel Salter, Special Agent In Charge of Dallas Field Division.