Zechariah 6:6

The black... therein go. — Better, that in which are the black horses went; literally, [were] going. It would seem that two chariots go into the “north country,” because there were there two powers to be overcome: viz., the remnant of the old Asshur-Babylonian and the Medo-Persian.

The south country is Egypt. After the battle of Marathon (B.C. 490), Egypt revolted from Darius, but it was re-conquered by Xerxes (B.C. 485). From that time onward it was continually in a state of revolt, till finally it was subdued to the Persian power by Ochos (B.C. 340). It was afterwards wrested from the hands of Persia by Alexander (B.C. 332).