A better Translation would be. Then the sign of the Son of Man in heaven. A sign was not to appear in the heavens, but the very destruction of the Temple was proof that God’s presence was no longer residence in the Temple and the Son of Man was ruling and reigning in heaven. The Temple Jesus said would be destroyed represented the (Presence of God the Shekinah of glory). Even after Jesus said. Your house (temple) is left to you desolate. (Matthew 23:38) They were a continuous offering of animal sacrifices as the Shekinah of glory was still residence in the Temple
The destruction of the Temple was proof to unbelieving Israel of the Son of Man Messiahship. Clearly, the Pharisees wanted proof that Jesus was truly the Messiah and the fulfillment of the Abrahamic Covenant.
The destruction of the Temple was also a sign that the Son of Man was seated in heaven bringing vengeance upon His enemies. A Psalm of David. The LORD said to my Lord, "Sit at My right hand, Till I make Your enemies Your footstool."(Psalms 110:1) The judgment would be a noticeable event. It will not be a quiet or hidden event, but one out in the open where everyone can see it,
All the tribes of the earth shall mourn. The tribes here is a reference to Israel, which has always been organized in a tribal structure. Israel is described in the book of Joshua as tribes. Chapter 18: 1-2
"And the whole congregation of the children of Israel assembled themselves together at Shiloh, and set up the tent of meeting there; and the land was subdued before them. And there remained among the children of Israel seven tribes, which had not yet received their inheritance.
Deuteronomy 33:4-5 Moses commanded a law for us, A heritage of the congregation of Jacob. And He was King in Jeshurun, When the leaders of the people were gathered, All the tribes of Israel together.
All the tribes of the earth will mourn This prophecy is cut from the same cloth as Zechariah which speaks of all the inhabitants of Jerusalem shall mourn. All the tribes or people of the land of Judea shall mourn. Let us examine this passage in its context and seek to discover its true significance.
And I will pour out on the house of David, and on the (inhabitants of Jerusalem), the Spirit of grace and prayers. And they (i.e., the inhabitants of Jerusalem shall look on Me whom they have pierced), and shall mourn for Him. As one mourns for an only son, and will be bitter over Him like the bitterness over the firstborn. In that day (i.e., when they look on Him whom they had pierced) the mourning (in Jerusalem) will be great, like the mourning of Hadad-rimmon in the valley of Megiddo. And the land shall mourn, families by families alone; the family of the house of David alone, and their wives alone; the family of Nathan alone, and their wives alone; the family of the house of Levi alone, and their wives alone; the family of Shimei alone, and their wives alone; all the families who are left, family by family alone, and their wives alone. Zechariah 12:10-14 (emphasis added)
Notice the emphatic time statements. The old inhabitants of Jerusalem were the ones that were going to mourn. The Hebrew word for "family" is mishpachah and it means "family; by extension a tribe or people." So, in essence, Zechariah was saying that the "tribes of the land" would mourn. Who were those "tribes?" "The inhabitants of Jerusalem."
The word "earth" is from the Greek word ge which can also be translated as area, region, or land. " In most of Revelation, is often better translated "land" (i.e. the promised land). According to Zechariah, the "earth" is the land of Palestine, specifically, Jerusalem. With all of this information, we can see that the "tribes of the earth" in Revelation 1:7 are the nation of Israel. The "earth" is Palestine. The land that would mourn is Jerusalem.
The blood flowing as high as the horses' bridles would portray the gravity of judgment (Revelation 14:20). The distance of 1600 stadia (about 180 miles) just happens to be the approximate length of the land of Palestine.
There is another verse in Zechariah that should not be over looked. "And I will pour on the house of David and on the inhabitants of Jerusalem the Spirit of grace and supplication; then (THEY WILL LOOK ON ME WHOM THEY PIERCED Yes, they will mourn for Him as one mourns for his only son, and grieve for Him as one grieves for a firstborn. (Zechariah 12:10)
Zechariah was the backdrop of the apostles John’s writings. Behold, He is coming with clouds, and every eye will see Him, (even they who pierced Him). And all the tribes of the earth will mourn because of Him. Even so, Amen. (Revelation 1:7)
For John Zechariah 12:10 was applicable to Jesus' crucifixion; but it would receive final fulfillment when "all the tribes of the earth" would mourn when they looked on him whom they had pierced. Because of the great calamities coming upon them. "the mourning in Jerusalem" would be great