The great tribulation of Mathew 24:21 was the time of Jehovah’s covenantal judgment upon Old Covenant Israel through the instrument of the Roman armies. It was the “days of vengeance and wrath” upon the Jews (Luke 21:20-23) for their murder of the prophets (Mathew 23:29-28), and their violation of the Old (Mosaic) Covenant (Deuteronomy 28 Luke 19:43-44). Both the Old Covenant and the Old Covenant nation (“Israel after to the flesh”) ceased to exist “covenantally” after the end of the Old Covenant world in AD70. The fact that the great tribulation was a covenantal judgment upon ethnic Israel, limits that tribulation to a first century fulfillment.