On this island a group of pig-men corruption creatures have horded a large amount of people that they keep in containment cells. I appears that it was once used as a prison, in which prisoners were forced to plow the fields... now the pig-men run the prison, though the fields have all gone dead. The pig-men have also been seen raiding local villages.

Why do they keep these prisoners instead of killing them outright? Who knows? This is an area of the corruption you will have to explore to find answers to.