The term, Barbary slave trade refers to slave trade that occurred in and around the Mediterranean Sea during the early modern period. The destination often was the Ottoman Barbary states. These states were mostly independent. The slaves were Christians from Europe. Arab and Berber Muslim pirates captured them in raids on slave ships, and in towns along the coast. The slaves came from Italy, Ireland, Spain, Portugal, France and the southwest of Britain. Sometimes they also came from Iceland or the Eastern Mediterranean. Enslaved Europeans would be freed if they converted to Islam.
The Ottoman Eastern Mediterranean was the scene of (much or) intense piracy. As late as the 18th century, piracy continued to be a "consistent threat to maritime traffic in the Aegean".
Robert Davis, author of Christian Slaves, Muslim Masters, estimates that slave traders from Tunis, Algiers and Tripoli kidnapped and transported 1 million to 1.25 million European Christians to North Africa, where they sold them into slavery, from the beginning of the 16th century to the middle of the 18th century. He assumes the number of Europeans enslaved by Barbary pirates remained roughly constant for a 250-year period.