Zechariah 6:6 - Matthew Poole's English Annotations on the Holy Bible

The angel signified by the black horses the executioners of God's just displeasure against sinners. Which are therein; in the second chariot, for nothing is said more of the first, (the red horses,) say some, because that bloody and cruel state was expired; but the sad things portended by the black horses are to come next on the scene. Go forth into the north country; Babylon, the whole kingdom of Babylon, which lay so much north from Judea, and because the metropolis lay north the whole kingdom is called the north country; which must feel the effects of these black horses, which was executed by the hands of the Medes and Persians, assisted by that squadron of angels which appeared in the second place. The white go forth after them; ministers of goodness, mercy, and kindness, went after the black, and their business was, say some, to dispose affairs for the benefit and joy of God's people in Babylon, whither these were sent to preserve them, to conduct them, and bring them back; and here was great work in this, for many staid behind till Ezra's and Nehemiah's time. The grisled go forth; the angels signified by these, and whose business, as some guess, lay in managing the Roman power, which was a mixture of many different people, and which were sometimes favourable, sometimes fierce and severe, to those they had to do with. Toward the south country; Egypt and Arabia, which lay south of Judea, and which the Romans did, though late, subdue; it may perhaps point at their invading Africa too, whose punishments were mixed somewhat with kindness and mercy more than the punishments of Babylon were.