hen King Josiah was 16 years old he began to seek the Lord. At the age of 20 he commenced to removing false religions from the Holy City. And, in fulfillment of ancient prophecies from the days of Jeroboam, Josiah burned the bones of dead pseudo-priests on an ancient altar in Bethel (1st Kings 13:2 & 2nd Kings 23:15). But, being young and very zealous, he didn't stop in Jerusalem or Bethel. Josiah spread his reformation beyond the borders of Judah. He carried it even into the land that had belonged to Israel… but which had been taken over by the Assyrians.
Then, Josiah began to repair the Temple. It had been built around 4 centuries earlier and had been both abused and remodeled several times. This was to be the last rectification of that structure before it's destruction by the Babylonians.
Josiah led his great move-in-the-right-direction PRIOR to the rediscovery of the Pentateuch by Hilkiah the priest. The entrance of God's Word onto the scene at that time was both a reward for the due diligence of Josiah as well as an energizing force to spur him on to higher spiritual ground. One thing happened right away: Josiah recognized that they were in a heap of trouble (2nd Chronicles 34:21). No doubt he was incredibly grateful when he heard from a prophetess that God was going to wait until after his death before pouring out His judgment upon Judah (2nd Chronicles 34:27 & 28). But of course, that relief would have been tempered by the realization that the damnation of Judah was inevitable. They were doomed to suffer a fate similar to that which Israel had seen previously.