John Trapp on Zechariah 6:6

Verſe 6. The black horſes which are therein, &c. Theſe Angels are appointed to ſeverall Countries. The black horſes to Babylon, (which lay North from Judaea) to inflict vengeance. The white horſes are ſent with them, to deliver the Church out of Babylon: and to bring their brethren for an offering unto the Lord, upon horſes, and in chariots, and in litters, and upon mules, and upon ſwift beaſts to Gods holy Mountain Jeruſalem, Eſay 66, 20.

And the griſled go forth toward the South countrey] To ſhew that the puniſhments of Egypt, and Arabia (which lay South-ward from Judaea) ſhould be ſomewhat mixed, and mitigated: they ſhould be in better caſe then Babylon: yet not ſo good, as that the Jews ſhould dream of a happy eſtate in thoſe countries: but rather repair to Judaea, and there keep them; ſith thoſe that are out of Gods precincts, cincts, are out of his protection, Pſal. 91.9, 10, 11, 12.