The "mountains of Israel", are the nations of Israel. This prophecy is directed to the Christian nations of today, and not Judah. Yet, most of the people of these nations don't even know who they are. Though Hosea 1:10 details Israel in the end times, most Christians simply chose not to believe God's word, but to follow their vain traditions.
Daniel_2:34-35, 44-45 gives us a clue as to what the "Mountain(s) of Israel" represent.
Daniel_2:34-35: - 34 You watched while a stone was cut out without hands, which struck the image on its feet of iron and clay, and broke them in pieces. 35 Then the iron, the clay, the bronze, the silver, and the gold were crushed together, and became like chaff from the summer threshing floors; the wind carried them away so that no trace of them was found. And the stone that struck the image became a great mountain and filled the whole earth.
Daniel_ 2:44-45: - 44 And in the days of these kings the God of heaven will set up a kingdom which shall never be destroyed; and the kingdom shall not be left to other people; it shall break in pieces and consume all these kingdoms, and it shall stand forever. 45 Inasmuch as you saw that the stone was cut out of the mountain without hands, and that it broke in pieces the iron, the bronze, the clay, the silver, and the gold — the great God has made known to the king what will come to pass after this. The dream is certain, and its interpretation is sure."
Daniel_ 2:44-45: - 44 And in the days of these kings the God of heaven will set up a kingdom which shall never be destroyed; and the kingdom shall not be left to other people; it shall break in pieces and consume all these kingdoms, and it shall stand forever. 45 Inasmuch as you saw that the stone was cut out of the mountain without hands, and that it broke in pieces the iron, the bronze, the clay, the silver, and the gold — the great God has made known to the king what will come to pass after this. The dream is certain, and its interpretation is sure."
The "Mountain(s) of Israel" are not the descendant tribes of Jacob. The Rock which comes down out of heaven in our near future, becomes the highest mountain in the earth; it represents the religion of the Israelites after they have repented and enters into a renewed relationship with the God of Abraham, Isaac and Jacob. The foundation stone of the Mountains of Israel is the truth that Jesus is the Son of God and the establishment of this teach co-insides with the establishment of God's Everlasting Kingdom.
The return of some of Abraham's descendants to the Land of Canaan, where Abraham had moved to at God's calling, in their own strength is the sign of the Fig Tree mentioned in Matthew_24:32 and the time span to when this present age will end is of the order of 91 plus years.
In Ezekiel_34 said that he would take the righteous remanent of Israel and gather them to himself in the fertile field where they will be found scattered in the ravines and along the streams all over the earth were they are living after being scattered to the four corners of the earth. God will teach/instruct all of the redeemed saints of Israel to become Priests for the nations of the earth to show the way into God's everlasting Kingdom through God's gift of salvation Grace. The Mountains of Israel are all about our Heavenly Father who the Saints of god worship.
Shalom