According to John J. Collins:

“In the prophets, the ‘end of days’ implies a definitive transformation of Israel in the distant future. Usually, the reference is to the time of salvation. A famous oracle that appears both in Isaiah 2 and Micah 4 says that in the end of the days the mountain of the Lord’s house will be exalted above all the mountains and all the people will stream to it. In Ezekiel 38, in contrast, the end of days is the time when Gog invades Israel, and so it is a time of distress, but one that culminates in the destruction of the invader. In Daniel Chapter 2 the Aramaic equivalent of the phrase if used with reference to Nebuchadnezzar’s dream of the four kingdoms and the final, everlasting kingdom of the God of heaven. In Ezekiel and Daniel, then, the concept was broadened to include not only the age of salvation but also that drama that leads up to it.”

From “The Expectation of the End in the Dead Sea Scrolls” in Craig A. Evans and Peter W. Flint (eds), Eschatology, Messianism, and the Dead Sea Scrolls (Grand Rapids: Wm. B. Eerdmans, 1997), p. 75.