The Seventy Years Exile
The northern kingdom of "Israel" (see The Northern Kingdom) had already been in exile for over a century (see The Galilee Captivity) when the southern kingdom of Judah (see The Southern Kingdom) had degenerated into the same sorry state that caused Israel's downfall. Judah, like Israel, had become so corrupt that the LORD would no longer tolerate them. But unlike Israel, for the sake of the coming Savior, the people of Judah, as a nation, would be allowed to return - after 70 years when the generation that had been corrupt had all died off. Ironically, most of those who went "home" had never been there before.
"And it shall come to pass, when seventy years are accomplished"
The fall and return of the people of Judah was prophesied, and fulfilled, according to the Word of God. They ignored His warnings to repent, but they could not ignore His wrath.
"25:1 The word that came to Jeremiah concerning all the people of Judah in the fourth year of Jehoiakim the son of Josiah king of Judah [see Kings of Israel and Judah and Israelite Dynasties], that was the first year of Nebuchadnezzar king of Babylon; 25:2 The which Jeremiah the prophet spake unto all the people of Judah, and to all the inhabitants of Jerusalem, saying, 25:3 From the thirteenth year of Josiah the son of Amon king of Judah, even unto this day, that is the three and twentieth year, the word of the LORD hath come unto me, and I have spoken unto you, rising early and speaking; but ye have not hearkened.
25:4 And the LORD hath sent unto you all his servants the Prophets, rising early and sending them; but ye have not hearkened, nor inclined your ear to hear. 25:5 They said, Turn ye again now every one from his evil way, and from the evil of your doings, and dwell in the land that the LORD hath given unto you and to your fathers for ever and ever: 25:6 And go not after other gods to serve them, and to worship them, and provoke me not to anger with the works of your hands; and I will do you no hurt.
25:7 Yet ye have not hearkened unto me, saith the LORD; that ye might provoke me to anger with the works of your hands to your own hurt.
25:8 Therefore thus saith the LORD of hosts; Because ye have not heard my words, 25:9 Behold, I will send and take all the families of the north, saith the LORD, and Nebuchadnezzar the king of Babylon, my servant, and will bring them against this land, and against the inhabitants thereof, and against all these nations round about, and will utterly destroy them, and make them an astonishment, and an hissing, and perpetual desolations. 25:10 Moreover I will take from them the voice of mirth, and the voice of gladness, the voice of the bridegroom, and the voice of the bride, the sound of the millstones, and the light of the candle. 25:11 And this whole land shall be a desolation, and an astonishment; and these nations shall serve the king of Babylon seventy years.
25:12 And it shall come to pass, when seventy years are accomplished, that I will punish the king of Babylon, and that nation, saith the LORD, for their iniquity, and the land of the Chaldeans, and will make it perpetual desolations [see The Writing On The Wall and Cyrus]. 25:13 And I will bring upon that land all my words which I have pronounced against it, even all that is written in this book, which Jeremiah hath prophesied against all the nations. 25:14 For many nations and great kings shall serve themselves of them also: and I will recompense them according to their deeds, and according to the works of their own hands." (Jeremiah 25:1-14 KJV)
Fact Finder: What was the condition of Jerusalem when the people of Judah began returning after 70 years in Babylon?
See Ezra and Nehemiah