zechariah 6:1 And I turned, and lifted up mine eyes, and looked, and, behold, there came four chariots out from between two mountains; and the mountains were mountains of brass. - Free Bible Online

      Zec 6:1-8. EIGHTH VISION. THE FOUR CHARIOTS.

      1. four chariots--symbolizing the various dispensations of Providence towards the Gentile nations which had been more or less brought into contact with Judea; especially in punishing Babylon. Compare Zec 6:8 ("the north country," that is, Babylon); Zec 1:15; 2:6. The number "four" is specified not merely in reference to the four quarters of the horizon (implying universal judgments), but in allusion to the four world kingdoms of Daniel.
      from between two mountains--the valley of Jehoshaphat, between Moriah and Mount Olivet [MOORE]; or the valley between Zion and Moriah, where the Lord is (Zec 2:10), and whence He sends forth His ministers of judgment on the heathen [MAURER]. The temple on Mount Moriah is the symbol of the theocracy; hence the nearest spot accessible to chariots in the valley below is the most suitable for a vision affecting Judah in relation to the Gentile world powers. The chariot is the symbol of war, and so of judgments.
      of brass--the metal among the ancients representing hard solidity; so the immovable and resistless firmness of God's people (compare Jer 1:18). CALVIN explains the "two mountains" thus: The secret purpose of God from eternity does not come forth to view before the execution, but is hidden and kept back irresistibly till the fit time, as it were between lofty mountains; the chariots are the various changes wrought in nations, which, as swift heralds, announce to us what before we knew not. The "two" may thus correspond to the number of the "olive trees" (Zec 4:3); the allusion to the "two mountains" near the temple is not necessarily excluded in this view. HENDERSON explains them to be the Medo-Persian kingdom, represented by the "two horns" (Da 8:3, 4), now employed to execute God's purpose in punishing the nations; but the prophecy reaches far beyond those times.

JFB.