"... A somewhat different, and potentially more sophisticated, approach was adopted by other writers during Second Temple times, and that was to fix on the larger unit of time called the jubilee. After all, the jubilee was mentioned as a significant measure of time within the Torah itself so it must be important! This 49-year unit was not only composed of seven sub-units of seven years apiece (“weeks of years”), but it itself could be thought of as a sub-unit of still larger blocks of time. So it was that some writers of this period liked to think of history as moving forward in units of ten jubilees apiece - 490 years. (Also reflected in Daniel 9:24-27, where seven weeks of seventy years equals 490 years ...) But even that might be on the small side; perhaps the main events in Israel’s history were demarcated by even larger units. The point was that, if one considered these larger numerical patterns, the idea of divine control of Israel’s history could be upheld despite the little surface disturbances that might spring up for a century or two and then disappear ..."