Respectfully, that's what you need to figure out before using it as a proof text to support the idea that it is speaking of Palestine.
It is a vision that is being related by Zechariah. It could be speaking of anywhere, or it could be speaking of a people/nation, etc.
Nowhere, in that chapter or the others before and after, does it speak of the Promised Land or anything of the like.
It was spoken well over 500 years before Christ came so it's not likely that it was speaking of the events around 1300 B.C. concerning the Promised Land that was given and then taken away. God had already destroyed the Israelites off of that land about 800 years prior.
I'm just analytically reasoning with you on this. If you can find something in Zechariah there that indicates it is speaking of Palestine, I'm happy to consider it. I just don't see it anywhere.
Zechariah give us a shocking preview of what is happening with Israel at His Second Coming! He also tells us what will happen immediately following the Second Coming of Christ, it includes what will take place throughout the land of Israel.
He tells us that Israel will be attacked and 2/3 of Israel will die, and God will leave 1/3 alive.
Zech. 13:8-9
"And it shall come to pass,
that in all the land, saith the LORD, two parts therein shall be cut off
and die; but the third shall be left therein.
And I will bring the third part through the fire, and will refine them as silver is refined, and will try them as gold is tried: they shall call on my name, and I will hear them: I will say, It is my people: and they shall say, The Lord is my God."
He explains the battle of Armageddon when the anti-christ will attack Jerusalem, and there is this terrible lose of life. But the Lord will intervene and save them at His Coming.
Zech. 14:1-3
"Behold, the day of the Lord cometh, and thy spoil shall be divided in the midst of thee.
For I will gather all nations against Jerusalem to battle; and the city shall be taken, and the houses rifled, and the women ravished; and half of the city shall go forth into captivity, and the residue of the people shall not be cut off from the city.
Then shall the Lord go forth, and fight against those nations, as when he fought in the day of battle."
While Israel has lost hope and see that they are about to be completely wiped out, Zech. records what happens.
Zech. 12:9-10
"And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem.
And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications:
and they shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn."
Israel will see Christ when He comes to destroy the anti-christ. They will finally know that Jesus of Nazareth was and is their Messiah. The mourning and bitterness are the sorrows of having rejected Him.
Throughout the land Israel will separate themselves according to the princely line of Christ to the priestly line of Christ to mourn over their Messiah. The princely line is the "house of David, and the "house of Nathan." The priestly line is the "house of Levi." The "families that remain" are the rest of Israel according to their tribes.
Zech. 12:11-14
"In that day shall there be a great mourning in Jerusalem, as the mourning of Hadadrimmon in the valley of Megiddon.
And the land shall mourn, every family apart; the family of the house of David apart, and their wives apart; the family of the house of Nathan apart, and their wives apart;
The family of the house of Levi apart, and their wives apart; the family of Shimei apart, and their wives apart;
All the families that remain, every family apart, and their wives apart."
Every Jew in Israel will feel guilty for crucifying their Messiah. This is when Paul said, "and all of Israel will be saved." Speaking of those who have survived the anti-christ.