Priest and King

Zechariah 6:1–3 (ESV) Again I lifted my eyes and saw, and behold, four chariots came out from between two mountains. And the mountains were mountains of bronze. 2 The first chariot had red horses, the second black horses, 3 the third white horses, and the fourth chariot dappled horses—all of them strong.

The seventh vision of Zechariah details a new day for the postexilic community, restored to the land and rebuilding the Temple. The image of chariots symbolizes that of warfare. The two mountains are a picture of the gateway of heaven. God is sending His army throughout the earth to trouble the nations that troubled Israel. History tells us that Babylon was conquered by the Medes and Persians, the Persians by the Greeks, and the Greeks by the Romans. 

Zechariah 6:4–7 (ESV) Then I answered and said to the angel who talked with me, “What are these, my lord?” 5 And the angel answered and said to me, “These are going out to the four winds of heaven, after presenting themselves before the Lord of all the earth. 6 The chariot with the black horses goes toward the north country, the white ones go after them, and the dappled ones go toward the south country.” 7 When the strong horses came out, they were impatient to go and patrol the earth. And he said, “Go, patrol the earth.” So they patrolled the earth.

The Northern country in scripture typically refers to Babylon and Assyria, the southern country usually refers to Egypt. Both of these directions represent some part of Israel's past - Egypt, where they learned idolatry and became enslaved, and Babylon, where they became commercially driven and worldly. God was going to remove this influence from Israel and also protect His people from their invasion in the future.

Since the episode in Babylon was the most recent, the Lord stipulates that the judgment upon them will bring His Spirit to rest concerning them:

Zechariah 6:8 (ESV) Then he cried to me, “Behold, those who go toward the north country have set my Spirit at rest in the north country.”

In the second half of the chapter, the text takes an entirely different direction. Three exiles from Babylon are brought together to provide silver and gold to make a crown for Joshua, the high priest:

Zechariah 6:11–12 (ESV) Take from them silver and gold, and make a crown, and set it on the head of Joshua, the son of Jehozadak, the high priest. 12 And say to him, ‘Thus says the LORD of hosts, “Behold, the man whose name is the Branch: for he shall branch out from his place, and he shall build the temple of the LORD.

Again, the Lord references the Branch, a chosen servant who will build the Temple of the Lord. This person was referenced back in Zechariah 3:8. But who is it? Isaiah speaks of him:

Isaiah 11:1 (ESV) There shall come forth a shoot from the stump of Jesse, and a branch from his roots shall bear fruit.

Jesse, by the time Zechariah was born, had long been dead. But someone from the son of Jesse, David, will arise and build God's house. Notice a hint about this Branch in verse 13:

Zechariah 6:13 (ESV) It is he who shall build the temple of the LORD and shall bear royal honor, and shall sit and rule on his throne. And there shall be a priest on his throne, and the counsel of peace shall be between them both.” ’

The text refers to a union of royalty and priesthood. Yet never before have these two positions been united. In fact, when Uzziah sought to burn incense as a priest, he was struck with leprosy and died. Saul also lost his kingship when he sought to offer the sacrifice at Samuel's delay. This union was strictly forbidden. 

But a branch from Jesse will come and be offered gifts from afar by those from the remnants of Babylon and Persia (magi in Matthew 2). He will be both King and Priest as Hebrews makes clear:

Hebrews 8:1–2 (ESV) Now the point in what we are saying is this: we have such a high priest, one who is seated at the right hand of the throne of the Majesty in heaven, 2 a minister in the holy places, in the true tent that the Lord set up, not man.

That temple He has built is not a building but His people, called out of the nations as a new Temple of the Holy Spirit. 

Zechariah is seeing the future Church, established and led by her Savior, Priest and King, long before Jesus was ever born.