I posted on this many years ago. Wiki has a good summation.:
The chronology of the Bible is an elaborate system of lifespans, 'generations', and other means by which the Masoretic Hebrew Bible (the text of the Bible most commonly in use today) measures the passage of events from the creation to around 164 BCE (the year of the re-dedication of the Second Temple). It was theological in intent, not historical in the modern sense,[1] and functions as an implied prophecy whose key lies in the identification of the final event.[2] The passage of time is measured initially by adding the ages of the Patriarchs at the birth of their firstborn sons, later through express statements, and later still by the synchronised reigns of the kings of Israel and Judah.[3]
The chronology is highly schematic, marking out a world cycle of 4,000 years.[4][5] The Exodus takes place in the year A.M. 2666 (A.M. = Anno Mundi, years of the world from creation), exactly two thirds of the way through the four thousand years; the construction of Solomon's Temple is commenced 480 years, or 12 generations of 40 years each, after that; and 430 years pass between the building of Solomon's Temple and its destruction during the siege of Jerusalem.[3] The 50 years between the destruction of the Temple and the "Decree of Cyrus" and end of the Babylonian Exile, added to the 430 years for which the Temple stood, produces another symmetrical period of 480 years.[4] The 374 years between the Edict of Cyrus and the re-dedication of the Second Temple by the Maccabees complete the 4,000 year cycle.[6]