Upvote:1
See https://lifehopeandtruth.com/prophecy/understanding-the-book-of-daniel/daniel-9/
This article quotes the Jamieson, Fausset and Brown Commentary. The 70 years was βthe exact number of years of Sabbaths in four hundred and ninety years, the period from Saul to the Babylonian captivity."
The cited article makes an interesting point: there were two overlapping 70-year exiles.