Interestsing topic, but, just using the Bible, these scriptures independently introduce a 70-year period from the last deportation, year 23 of Nebuchadnezzar, until the 1st of Cyrus:
Jeremiah 44:14 And there will come to be no escapee or survivor for the remnant of Judah who are entering in to reside there as aliens, in the land of Egypt, even to return to the land of Judah to which they are lifting up their soul[ful desire] to return in order to dwell; for they will not return, except some escaped ones.’”
Jeremiah 44: 28 And as for the ones escaping from the sword, they will return from the land of Egypt to the land of Judah, few in number; and all those of the remnant of Judah, who are coming into the land of Egypt to reside there as aliens, will certainly know whose word comes true, that from me or that from them.”’
2 Chronicles 36: 20 Furthermore, he carried off those remaining from the sword captive to Babylon, and they came to be servants to him and his sons until the royalty of Persia began to reign; 21 to fulfill Jehovah’s word by the mouth of Jeremiah, until the land had paid off its sabbaths. All the days of lying desolated it kept sabbath, to fulfill seventy years."
DISCUSSION: This is why the discussion by Olof Jonsson regarding the 70 years of servitude is irrelevant to whether or not the land was desolated for 70 years. That's because as you note in the above 2 quotes, a few of the people who would not be killed by Nebuchadnezzar who had ran down to Egypt, would return to Judea. These last remaining ones were deported to Babylon in year 23 of Nebuchadnezzar. But it is these specific ones who were to be in servitude to Babylon for precisely 70 years. Further, it is in direct correlation with the 70 years of paying back the sabbaths, whch were a period of 70 years, spread out over all the 12 tribes.
That is, 390 years of error for the 10 tribes is 39 years each.
Judah ruled slightl longer, so they were assigned 40 years.
390 + 40 is 430 years.
This was the unfaithful years of not keeping the agricultural sabbaths. The agri-sabbaths were two: One every 7 years and one every 50 years. So note what happens when we divide 430 years of failed sabbaths by these two agri-sabbaths:
430/7 = 61.4
430/50 = 8.6
Thus we do have a Biblical reference to explain why the land must be desolated for 70 years. Since Jeremiah 44:14 and 28 places people in the land right up until the last deportation in year 23 (Jer. 52:30), the land was still being worked or producing up until that time and thus was not considered to be resting. So until the last official Jews were actually removed off the land, the 70 years of keeping sabbath could not take place. Thus the 70 years of desolation of the land and the 70 years of exile are the same 70-year peeriod, but only applies to those of the very last deportation.
Now, Olof Jonsson might have done a bang-up good job of proving or asserting that the nations were under Babylonian rule for 70 years. But Jeremiah's prophecy about 70 years is linked with the last deportation, the servitude of these specific people who were deported at the last deportation who were from Egypt.
Now everybody cannot serve exactly 70 years. Only one group can serve that long. Turns out, 70 years is the minimum period of servitude. Others deported in the accession year of Neb2 (Daniel, et al), the 7th year (Ezekiel, et al), the 8th year (King Jehoiachin, et al), the 9th and 11th years, all served longer than 70 years. The last deportation was year 23, so Daniel who was deportged in the accession year of Neb2 would have served 24 years longer than 70 years, some 94 years! If he were ten years old when he was deported, he would have left Babylon at age 104. He was still alive in year 3 of Cyrus, so he would have been about 107. He was very old and feeble at the time.
Furthermore, the Jews were still in exile during the entire 6-year rule of Darius the Mede. Zechariah 1 tells us that 70 years after the fall of Jerusalem expired in the 2nd year of Darius the Mede, while the Jews were still in exile. As we recall, Daniel was still in the service of Babylon during the time of Darius the Mede when he was thrown into the lion's den.
Zechariah 7, tells us that 70 years after the mourning of Gedeliah in the 7th month expired in the 4th year of Darius the Mede while the Jews were still in exile, wondering when God would show mercy to Jerusalem and the cities of Judea, meaning when would they be allowed to be inhabited again. Gedeliah was killed a year after the fall of Jerusalem in the 7th month. Word of this reached Babylon by the next year when they began to fast and mourn in honor of his death. So the mourning began 2 years after the fall of Jerusalem. That is why 70 years following the mourning of Gedeliah in the 7th month in year 4 of Darius, is 2 years after 70 years expires in year 2 of Darius. So just using the Bible we can confirm two things:
1) That 70 year after the fall of Jerusalem does not end the 70 years of Jeremiah's prophecy.
2) That Dariuis the Mede must have ruled for 6 years before Cyrus came to the throne.
The above simply reflects that the time period from the fall of Jerusalem to the 1st of Cyrus is a period of 74 years. Jerusalem fell in the 19th year of Nebuchadnezzar. Again, as Zech 1 points out, 70 years from the "denunciation" of Jerusalem and the cities of Judea expired in the 2nd year of Darius. The mourning for Gedaliah began 2 years later and 70 years expired in the 4th of Darius. Even so, since the 70 years of servitude of those last deported in year 23 was not yet up and would not expire for another 2 years, the Jews were still in exile during this time and would only come out of exile when Cyrus began to rule. That is why it is very important to understand why the Bible is quite specific to call Darius, Darius the MEDE, and Cyrus, Cyrus the PERSIAN. That is because the end of the Babylonian Empire would end when Cyrus took over the entire Medo-Persian Empire, which was after a 6-year rule first by Darius the Mede. Thus Darius the Mede is not considered to be the "royalty of Persia" but the royalty of the Medes. That's why 2 Chronicles 36 ends the 70 years when the "royalty of PERSIA begins to rule." Of course, Darius the Mede, was the grandson of Nebuchadnezzar. The Medes and the Babylonians were once close allies and there was a state marriage between the Medes and the Babylonians. The father of Darius the Mede, Cyaxares, married the daughter of Nebuchadnezzar.
So, in effect, the Babylonians were quite cool to have Darius the Mede rule over them since he was a legitimate Bablonian king himself, a royal descendant of Nebuchadnezzar II.
In addition, the #1 king of Babylon, Nabonidus, was not killed when Belshazzar was killed. Apparently, he remained at-large and thus still the official ruler of Babylon, until Darius the Mede abdicated to Cyrus, at which time Nabonidus was placed under house arrest, officially ending the Neo-Babylonian kingdom.
CHRONOLOGY, BIBLE VS SECULAR: Now the above means that the NB records and the Biblical records are in conflict. It means the Bible claims the NB Period is some 25-26 years longer than the secular records. So one of these histories was revised. But as soon as we start looking at the authenticity of the Babylonian historical records, we find all their palace records, the Nabonicus Chronicle, Cyrus Cylinder, and Babylonian Chronicle are all "copies" from the period of Darius II or later. So that's the end of that competition. A "copied" record is automatically presumed to be a revised document, so from this we learn the Persians revised the NB records, removing some 26 years from the NB kinglist. The Bible reflects the true original chronology. Of course, this leads to the obvious suspicion that the Persian Period was expanded by these removed years.
This affects Olof Jonsson's conclusions because he supports the 539 BCE chronology for the fall of Babylon as well as the 5878 BCE chronology for the fall of Jerusalem. Neither of these dates can be considered credible compared to the Biblical record since they would reflect adjustments made during the Persian Period. In addition, since 539 BCE is part of this adjustment, 607 BCE which is based on the 539 BCE dating, considered a "pivotal date" by the WTS, would be incorrect as well. Of course, 607 BCE would have dated, per the Bible, the year of the last deportation in year 23 and not the last deportation in year 18 or 19. So 607 BCE is a totally non credible date. But so is 587 BCE or 539 BCE per Biblical dating.
Strict Biblical chronology requires the 1st of Cyrus to fall in 455 BCE. That means the last deportation must be dated to 525 BCE, year 23 of Nebuchadnezzar. Four years earlier would be the true date for the fall of Jerusalem in 529 BCE.
That is, if you want to follow the Bible.
Just in passing, C.O. Jonsson used to consider the VAT4956 as the most important ancient text for dating the NB Period. It does, indeed, date year 37 to 568 BCE for most references. But in Lines 3 and 14, there is a match for 511 BCE lunar positions. This is critical in the context of 455 BCE, since if we use 455 BCE to date year 23 of Neb2 to 525 BCE, then year 37 falls in 511 BCE. Thus this can hardly be considered a coincidence. Thus it appears the VAT4956 was created in a diary form to look like a politically correct document confirming the revised chronology. But instead it was used to hide secret lunar positions from the original year 37 of Neb2 in 511 BCE. Making that assessment or presumption or conspiracy theory, whatever, still gives us only one alternative dating for the reign of Nebuchadnezzar, with his 23rd year falling in 525 BCE, which is the precise year we get when the 1st of Cyrus falls in 455 BCE and the last deportation falls 70 years earlier.
So, the 70-year issue has long been corrected at this point, along with the phony NB years revised by the Persians.
The reason why modern scholars don't acknowledge the revisions by the Persians is because the ancient timeline is a modern conspiracy. That is, bythe time of Christ, Jews were revising their records to conform with the revised timeline, including the Book of Esther. Exposing the true timeline would prove that Jesus Christ is the true messiah, arriving 483 years after the return from Babylon in 455 BCE. Jews, who need to deny Christ, are thus not served by this truth and this represents a conflict of interest for them. So Jewish scholars would not be expected to betray their faith by acknowledging anything but the false timeline. In that context, we find it interesting that Hermann Hunger, who translates the VAT4956 got caught lying about several lines in the VAT4956. If he understood from Jewish history that the current timeline was incorrect (i.e. Jews have always noted the Persian Period was too long and with too many kings), and thus the VAT4956 represented the revised timeline and not the true timeline, he might have considered it a betrayal to draw any real attention to this text being fraudulent. Line 18 of the text would have created suspicion if correctly translated. But that's another conspiracy theory. This "error" has been pointed out to him and he has apologized for it, however, claims he "does not remember" WHY he inserted the false information.
So with scholars lying and being deceptive about rare historical evidence supporting the true timeline, it is understandable why these revisions have not been corrected. But at this point, we certainly cannot presume the original timeline is not actually known by some scholars, but those scholars seem to consistently feel the need to cover this up.
But at least we know the Biblical truth about this. The Bible dates the fall of Jerusalem in 529 BCE. The 70 years of desolation was from 525 BCE to 455 BCE. You don't have to accept this as correct, if you trust secular history more, but that is what the Bible's timeline must remain, regardless.