Albert Barnes Commentary 2 Kings 17:1

"In the twelfth year of Ahaz king of Judah began Hoshea the son of Elah to reign in Samaria over Israel, [and reigned] nine years." — 2 Kings 17:1 (ASV)

In the twelfth year - Compare 2 Kings 15:30. The history of the kingdom of Israel is in this chapter brought to a close.