Heidegger's Bible Handbook: Zephaniah: Chronology

2.  He prophesied in the days of Josiah, a history of whose times is compared with the argument of this Prophecy.

Zephaniah prophesied בִּימֵ֛י יֹאשִׁיָּ֥הוּ, in the days of Josiah, Zephaniah 1:1.  If his times, which are described in 2 Kings 22, etc., and 2 Chronicles 34, be considered, the argument of the Prophecy will be quite evident.  Although Josiah the King, second to no one in piety and zeal for the propagation of the glory of God, according to the rule of the Divine Law brought forth by Hilkiah, had abolished false Religion, and had renovated the true, he had few supporters and approvers in so holy a purpose, whether of the Princes, or of the people, or of his very own sons, not greatly approving of the paternal arrangements.  The response of Huldah, 2 Kings 22:15, etc., and the events of following times, sufficiently demonstrate this.  With Josiah dead, they soon returned to impiety and their former disposition.  Hence Zephaniah, after the example of Jeremiah exhorts to repentance, and urges them, that they might put away the impiety shut up in the heart, and make use of in words, and exercised in the innermost parts of private houses.  In the first place indeed, he reproves their scandals, impiety, injustice, pride, and immodesty in the adorning of the body, and denounces affliction:  and finally, after they have been afflicted, he promises restoration, predicts the destruction of their enemies, and prophesies that it is going to come to pass, that Jerusalem is going to be more illustrious than it has ever been, with all nations coming together to its worship, which is exhibited most fully in the Kingdom of Christ.