Two men have been jailed for crimes relating to prostitution, modern slavery and running nine brothels.
Mo Quan Zhou, 45, and Meyrick Bramhill-Purchase, 64, have been sentenced to a total of 10 years after being found guilty following a 10-week trial.
The pair operated two brothels in Chesterfield, two in Derby, and five in Lincoln from May 2015 to May 2017.
Police said vulnerable Chinese and Malaysian women were found at the brothels after being trafficked.
Zhou, of London Road, Derby, was jailed for five-and-a-half years while Bramhill-Purchase of Muntjac Way, Witham St Hughs, Lincolnshire, has been handed a four-and-a-half year sentence.
The investigation began in May 2015 after a concerned letting agent reported suspicions that a house in Friars Lane, Lincoln, was being used as a brothel.
A man who visited the London Road brothel in Derby also called police when he became concerned a woman had been trafficked.
Police said typically one man would act as a minder for the women and take the money for Bramhill-Purchase and Zhou.
Investigators also found the men paid for adverts on escort websites.
Insp Harry Rai said the men were "controlling" women and the brothels were "bringing misery" to communities.
He added: "These women were very vulnerable. Many of them had overstayed their visas and were desperate to remain in the UK in order to avoid an even worse existence in their home countries."
Zhou was found guilty of conspiracy to facilitate the travel of another with a view to sexual exploitation.
Both Zhou and Bramhill-Purchase were convicted of conspiracy to facilitate the travel of another with a view to exploitation, conspiracy to control prostitution for gain and one count of removing criminal property.