וַיַּֽעֲמִ֣ידוּ דָבָ֗ר לְהַעֲבִ֨יר ק֤וֹל בְּכָל־יִשְׂרָאֵל֙ מִבְּאֵֽר־שֶׁ֣בַע וְעַד־דָּ֔ן לָב֞וֹא לַעֲשׂ֥וֹת פֶּ֛סַח לַיהוָ֥ה אֱלֹהֵֽי־יִשְׂרָאֵ֖ל בִּירוּשָׁלִָ֑ם כִּ֣י לֹ֥א לָרֹ֛ב עָשׂ֖וּ כַּכָּתֽוּב׃
Rashi on II Chronicles
from Beersheba to Dan This is the boundary of the Ten Tribes.
Rashi on II Chronicles
because for many years The meaning is that many years had passed in which they had not performed it according to its law.