The book of Zechariah was written when God's chosen people was subject to the Persian Empire. Darius I was king at the time.
The prophet admonishes the people not to repeat the sins of their forefathers. He promises that God would bless them. He would send them their King, who would come to them riding on a donkey and who would establish His rule over all the earth.
Among Zechariah's other amazing prophecies, we read: "They shall look upon Me, whom they have pierced." We recall that this prophecy was fulfilled when a soldier pierced the side of Jesus as He was hanging on the cross.
Note that this e-book, like all my works on the minor prophets, are simple presentations designed for people who are not acquainted with prophetic literature. Experts might be disappointed, but they might be interested in some of my analytic passages.
This was more difficult than the other minor prophets that I treated, but I think that Lord gave me an insight into the meaning.