When the powerful horses went out, they were straining to go throughout the earth. And he said, “Go throughout the earth!” So they went throughout the earth. Zechariah 6.7
The 8th and final of Zechariah's visions echoes the first and resonates - through Scripture and through history - as the inspiration behind John's 4 horsemen of the Apocalypse. What do they represent? In a word: judgment - God's judgment on those who have oppressed God's people. Most aggressors swooped in from the north, though the Egyptians were a constant threat from the south and the Philistines from the west. No mention of the east but few ventured across the barren expanse of the Arabian desert, so perhaps that does not warrant a mention?
The apparent and happy outcome is "rest" (verse 8) or, we might say, peace. Notice that it is God who has taken the initiative and who has secured the outcome. To this day we depend on God for the meeting of our personal needs and for the resolution of more general and widespread crises. In his grace he employs us in his service but, whether it is the future of the planet or the salvation of our souls, the message of Zechariah - and indeed of the whole Bible - is that we must first look to God. Notice, that does not mean do nothing anymore than it cautions us against rushing off in our own strength. We should care and we should act - yet compassionate action which is faithful and effective - begins on our knees...