Gog and Magog
According to some commentators, the war of Gog and Magog envisioned in Ezekiel 38 is expected to occur in the end of days. This is described to be a climatic war that is said to occur at the end of the Jewish exile. Persia and other powers from the north are said to attack Israel, where the God of Israel reveals himself and ends the war. Radak comments on Zechariah 14, that in the end of days Jerusalem will be the battle ground of Gog and Magog.
According to other commentators the long exile has already made up for it and it will no longer occur.
Read more about this topic: Jewish Eschatology