Slavery for the purpose of sex is a reason for human trafficking.
Slavery in early medieval Europe was so common that the Catholic Church repeatedly prohibited it, or at least the export of Christian slaves to non-Christian lands, as for example at the Council of Koblenz (922), the Council of London (1102) (which aimed mainly at the sale of English slaves to Ireland) and the Council of Armagh (1171)
 Slavery has been described as "very important in medieval Korea, probably more important than in any other East Asian country, but by the 16th century, population growth was making [it] unnecessary"

