Jamieson, Fausset and Brown on 2 Kings 23:15-20

15-20. Moreover the altar that was at Beth-el, &c.--Not satisfied with the removal of every vestige of idolatry from his own dominion, this zealous iconoclast made a tour of inspection through the cities of Samaria and all the territory formerly occupied by the ten tribes, destroying the altars and temples of the high places, consigning the Asherim to the flames, putting to death the priests of the high places, and showing his horror at idolatry by ransacking the sepulchers of idolatrous priests, and strewing the burnt ashes of their bones upon the altars before he demolished them.