When is the yovel in effect?
According to a baraita quoted by the Gemara on yesterday’s daf, with the beginning of exile during the first Temple period, the yovel no longer applied. This is based on the passage in Vayikra (25:10) that requires that during the Jubilee year the courts must “proclaim liberty throughout the land unto all the inhabitants thereof.” Only if “all the inhabitants” are residing in the land of Israel does this law apply.
The Gemara on today’s daf questions whether the yovel was not in force at the end of the first Temple period, for we find that the prophet Yirmiyahu calls on the people to free their slaves (see Yirmiyahu 34:14), which is understood by the Gemara to include even an eved nirtzah – a Jewish slave who asked to remain with his owner (see Shemot 21:6) – who is set free at the beginning of the Jubilee year.
Rabbi Yoḥanan responds that Yirmiyahu succeeded in bringing back at least some of the exiled people from the northern tribes, and that there was a period when the Judean king, Amon, ruled on all of Israel. It was at that time that the yovel was reestablished.
From the straightforward flow of the Gemara it appears that Rabbi Yoḥanan’s response is presented in order to explain why the Jubilee year was kept during second Temple times. Based on this approach, Rabbeinu Tam argues that Ezra the Scribe must have been successful in bringing with him at least some remnants from each one of the tribes and arranged for them to settle in their ancestral lands. According to this view, even during the second Temple the yovel was in effect on a biblical level. The Ramban disagrees, suggesting that Rabbi Yoḥanan’s statement comes only to explain the reality during first Temple times. During the second Temple period, Jubilees were counted on a Rabbinic level in order to keep track of the Sabbatical year cycle.