the third year of the reign of Hoshea … over Israel: Hezekiah became co-ruler with his father, Ahaz. Hoshea started his reign in 732 BC, so Hezekiah began around 728 BC at age twelve. When Ahaz died in 715 BC, Hezekiah became the only ruler at age twenty-five. He then ruled for twenty-nine years from 715 to 686 BC.