The last years of Judah were spent between the fall of the north to Assyria in 722 B.C.E. and the fall of Jerusalem to Babylon in 586 B.C.E. Israel, the old northern kingdom, was now an Assyrian province. Assyria remained strong early in this period, annexing Egypt in 664 B.C.E. under Ashurbanipal. Shortly after the end of Ashurbanipal's reign, however, the Neo-Babylonians, aided by the Medes, crushed the Assyrians and established their own empire under Nebuchadnezzar, sacking Nineveh in 612 B.C.E. and defeating Egypt at Carchemish in 605 B.C.E.
Ahaz, who had joined with Assyria in opposing the Syro-Ephraimite coalition, despite Isaiah's warnings, remained loyal to Assyria. Ahaz was followed by Hezekiah, who enacted sweeping religious reforms. Assuming an Assyrian collapse, and against Isaiah's advice, Hezekiah aligned himself with Egypt and Babylon and tried to regain Judean independence. His rebellion was stopped in 701 B.C.E. by Sennacherib of Assyria, despite his fortification of the city and construction of Hezekiah's Tunnel, which brought water from the Spring of Gihon to the pool of Siloam inside the city. Jerusalem was spared destruction by the payment of heavy tribute.
Josiah (640-609 B.C.E.) successfully rebelled against Assyria, reestablished control over some of what had been lost, and instituted widespread religious reforms purging the idolatrous Assyrian practices begun with Manasseh and Amon. These reforms were spurred in 621 B.C.E. by the discovery of a scroll in the temple. This scroll may have been an early form of our present book of Deuteronomy (or at least, chapters 12-26). Josiah died in battle at Megiddo in 609 B.C.E. attempting to prevent Egypt from going to the aid of Assyria against the Neo-Babylonians. The prophets Zephaniah, Nahum, Habakkuk, and Jeremiah all preached at this time, warning of political and military disaster.
In 598 B.C.E., Nebuchadnezzar marched against Jerusalem, occupied the city, and deported the fruit and flower of the population to Babylon, including King Jehoiachin and the royal family. Zedekiah became a puppet king for the Babylonians. In 589 B.C.E., the Judeans rebelled again. Babylon returned in 588 B.C.E., devastating Judah, and in 586 B.C.E., Jerusalem itself was destroyed and the temple burned. Zedekiah was forced to witness the execution of his sons immediately before his eyes were gouged out and he, along with many Judeans, was deported to Babylon. Thus, the kingdom of Judah came to an end.