From Gibbons Decline And Fall, after describing the Muslim taking of Hagia Sophia:
At the same hour a similar rapine was exercised in all the churches and monasteries, in all the palaces and habitations, of the capital; nor could any place, however sacred or sequestered, protect the persons or the property of the Greeks. Above sixty thousand of this devoted people were transported from the city to the camp and fleet, exchanged or sold according to the caprice or interest of their masters, and dispersed in remote servitude through the provinces of the Ottoman empire.
Sounds like slavery to me