2 Chronicles 34:6

And so did he in the cities of Manasseh, and Ephraim, and Simeon, even unto Naphtali, with their mattocks round about.

Cross-reference

2 Chronicles 31:1 describes Hezekiah's people destroying altars in Ephraim and Manasseh — a direct parallel to Josiah's similar reform.

2 Chronicles 30:1 Historical context

2 Chronicles 30:1 shows Hezekiah sending letters to Ephraim and Manasseh for Passover — same northern regions Josiah later purges of idols.

2 Kings 23:15-20 gives the parallel account of Josiah destroying the Bethel altar and high places in Samaritan cities.

2 Kings 23:19 is the parallel account of Josiah removing high places in Samaria's cities, matching the same reform.