Yes by the babylonians and it was the Persians who freed them. What is your point?
The author of this article claims that the institution of slavery did not exist in ancient Persia.
However, Queen Esther, exact date unknown but certainly decades after the overthrow of Babylon, mentions the possibility that her people might have been sold into slavery by the King instead of being massacred.
If slavery did not in the empire, how could this have been even a possibility?
To be perfectly fair, the term "slavery" covers a multitude of relationships, with enormous variability as to status, rights, etc. down through history. All Persians considered themselves "slaves of the King." Since the King had power of life and death over all his subjects, this was indeed true in a very real sense.