597 and 587 BCE are given as dates, not estimates, and the reason is a Babylonian tablet and an astronomical framework that has nothing to do with the Bible.
Two events, not one
The end of the kingdom of Judah happened in stages, and collapsing them is the commonest error in popular accounts. In 597 BCE Nebuchadnezzar took Jerusalem, removed its king and installed a replacement. About a decade later the city was taken again and the temple destroyed.
The first of those has a precise external date. The second does not have one of the same quality, and the difference matters.
What fixes 597
The Jerusalem Chronicle, a Babylonian administrative chronicle held in the British Museum, records in its entry for Nebuchadnezzar’s seventh year that he encamped against the city of Judah, seized it, captured its king, appointed a king of his own choice, and took heavy tribute to Babylon. The entry is dated to the second day of the month of Addaru.
Converting that to a Julian date is not guesswork. Babylonian regnal years and month names sit inside a chronological framework built from dated astronomical observations — eclipse records and planetary positions preserved on other tablets — which can be checked against modern computation. The conversion gives March 597 BCE.
That is why this date is quoted with a confidence that most ancient dates do not deserve. It rests on a contemporary administrative record, dated by a calendar that is independently anchored.
Why 587 is less firm
The chronicle tablet breaks off before the destruction. The date for the second capture and the burning of the temple therefore comes from the biblical text’s own regnal notices, cross-referenced with the Babylonian chronology established elsewhere.
The result is a two-way split in the scholarly literature between 587 and 586 BCE, turning on how the regnal years are counted — whether a king’s accession year is counted as his first, and which reckoning the biblical source used. Both dates are defended by serious specialists, and this site gives 587 with the alternative noted rather than presenting a consensus that does not exist.
What this shows about dating in general
A date is only as good as the chain behind it, and the chain here has three links: a contemporary record of the event, a calendar system, and a way of tying that calendar to ours. Break any link and the date becomes an estimate.
Most events in the Hebrew Bible have none of the three. That is why this archive treats a firmly dated event as a rare asset rather than a normal condition, and why it says which of the two dates in this study is which.
Related: the overviews of 2 Kings and Lamentations, and the Neo-Babylonian timeline.