כִּי לֹא נַעֲשָׂה כַּפֶּסַח הַזֶּה מִימֵי הַשֹּׁפְטִים אֲשֶׁר שָׁפְטוּ אֶת יִשְׂרָאֵל וְכֹל יְמֵי מַלְכֵי יִשְׂרָאֵל וּמַלְכֵי יְהוּדָה
For such a Passover was not observed from the days of the judges that judged Israel, nor in all the days of the kings of Israel and the kings of Judah.
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.