The prophetic expression describing the time of Judah’s captivity as “seventy years” (Jeremiah 25:11,12; 29:10) has prompted speculation throughout the history of Biblical interpretation.

• Jehovah’s Witnesses assert that the Babylonian exile was a literal 70 years. They use the historical and archaeologically and astronomically proven date of the return, 537 BCE. But, with no proof whatsoever, they claim the exile began in 607 BCE. Why? Because, for over a hundred years, they have used the 607 date as a springboard to arrive at their important 1914 date, through patching together a series of complicated calculations derived from various unrelated scriptures. Up until 1928, they even used various measurements from inside the Great Pyramid of Egypt to arrive at 1914. They have so much invested in their 1914 date that they can’t seem to bring themselves to abandon the foundational 607 BCE date, in spite of overwhelming contrary evidence.
• The numeric systems of the ancient Near East were predom­inantly hexagesimal (based upon ascending groups of six), and the maximum number that could be easily calculated was 60. It is possible that the number 70 may have been used to symbolically represent a numeric value of staggering proportions or perhaps the number of years representing a generation (Psalm 90:10; Isaiah 23:15). The number 70 may have been used in the same way in Jeremiah 25, as in Isaiah’s announcement that Tyre would be desolate for 70 years (Isaiah 23:15,17), and a similar usage may be reflected in the Black Stone of Esarhaddon, in which Marduk decreed displeasure against Babylon for 70 years.
• The original context of the prophetic word was the fourth year of Jehoiakim of Judah and the first of Nebuchadnezzar (605 BCE.). “Until this very day” (Jeremiah 25:3) Jeremiah anticipated a period of dev­astation and judgment during which Judah would serve Babylon. Upon the completion of this interval, the prophet predicted that divine judgment would be brought upon Babylon (vv. 12-13) and Judah and that Jerusalem would be restored (Jeremiah 29:10-14).

King Jehoiakim began to serve the Babylonians by politi­cally consigning Judah as a vassal state in 605 B.C. (2 Kings 24:1). Almost 70 years later Babylon was captured by the Persians, bringing about the end of Babylonian sovereignty over Judah and initiating the process of the return from exile under Cyrus the Great (539/538 BCE.). The return was finished by 537/536 BCE.

The interpretation of Jeremiah’s 70 years of captivity as the approximate period between 605-539/538 B.C. is more explic­itly stated in later Biblical texts, and is proven historically, archaeologically, and astronomically. According to 2 Chronicles 36:20-21, divine judgment was executed against Judah by the Babylonian king in that “they became servants to him and his sons until the kingdom of Persia came to power… until the sev­enty years were completed.” Both the Chronicler (2 Chronicles 36:22 NIV) and Ezra (Ezra 1:1) interpreted the edict of Cyrus, which authorized the return of the exiles and the rebuilding of the temple in Jerusalem (Ezra 1:2-4; 6:1 -12), as the fulfillment of the prophetic word of Jeremiah.

A different calculation of the “seventy years,” and thus a different 70 year period, appears to underlie Zechariah 1:12 and Zechariah 7:5. There it denotes the interval between the physical destruction of the temple (587/586 B.C.) and the rebuilt temple’s dedication (515 B.C.).

ONE SOURCE: NIV Archaeological Study Bible