Rashi explains why such a Passover was impossible “all the days of the kings of Israel and the kings of Judah.” Jeroboam, the first king of the northern kingdom, set up two golden calves and did not allow his people to go to Jerusalem. Now, after the ten Tribes were exiled, Jeremiah brought back representatives of each Tribe. This was the first Passover in centuries that had members of every Tribe at the Temple.