After seventy years - literally, according to the measure of the fulfillment of 70 years for Babylon. The 70 years (Jeremiah 25:11 note) are primarily the length of the Babylonian empire, and only in a secondary sense that of the Jewish exile.
Related Commentaries of Jeremiah 29:10
Jeremiah 29:10
10 For thus saith the LORD, That after seventy years be accomplished at Babylon I will visit you, and perform my good word toward you, in causing you to return to this place.