“in the days of Hezekiah king of Judah.” In the days of Hezekiah, descendants of the tribe of Simeon had grown powerful enough to move east into the hill country of Judah and dispossess some of the native peoples that still lived there.

“devoted them to destruction.” That is, destroyed them.

[For more on things “devoted” to Yahweh and devoted to destruction, see commentary on Joshua 6:17.]