Ну вообще-то это как бы основная теория происхождения слова slave. Вот из Оксфордского словаря:
Word Origin
Middle English: shortening of Old French esclave, equivalent of medieval Latin sclava (feminine) ‘Slavonic (captive)’: the Slavonic peoples had been reduced to a servile state by conquest in the 9th cent.
Word Origin
Middle English: shortening of Old French esclave, equivalent of medieval Latin sclava (feminine) ‘Slavonic (captive)’: the Slavonic peoples had been reduced to a servile state by conquest in the 9th cent.
https://thechive.com/2012/12/06/apparently-you-can-make-an-ak-47-out-of-just-about-anything-25-photos/