Twelve Thai nationals and five Americans were charged with illegally transporting hundreds of women from Thailand.
Their victims were forced to work as prostitutes across the US.
A US lawyer said the ring promised poor women a bright future, then "forced them to live a nightmare".
The women were driven into prostitution in Chicago, Los Angeles, Washington DC, and other cities, to pay off "bondage debts" of between $40,000 and $60,000 (£31,000 and £47,000).
