The definition of "Palestine" was first expanded when the conquering Romans (see Ancient Empires - Rome) used the name Syria Palaestina during the second century before Jesus Christ. They used it to designate the southern portion of the province of Syria, which then took in Roman occupied Judea, including Jerusalem.
In modern times, the popular definition of Palestine was again greatly inflated after the First World War. Britain, which then held control of the land of Israel under a mandate of the League of Nations (British control eventually made possible the birth of the modern state of Israel, thereby fulfilling a vital Biblical element of Prophecy), revived the name as an official title for practically all of the land - from Dan to Beersheba, and from The Mediterranean Sea to The Jordan River. And so it has been ever since.
Humans have been fighting over "Palestine" for a very long time. A vital, very often overlooked point of the struggle, which continues right this very minute, is that the earth belongs to God. It is His property. He created it, and He has held full ownership of it before humans ever existed.
So, who does the Owner of the land say is to be living there, not for their benefit, or out of any sort of favoritism, but to fulfill the practical, physical aspects of His plan of salvation for all people, of all nations? Let's see:
"Jacob left Beersheba, and went toward Haran. And he came to a certain place, and stayed there that night, because the sun had set. Taking one of the stones of the place, he put it under his head and lay down in that place to sleep. And he dreamed that there was a ladder set up on the earth, and the top of it reached to heaven; and behold, the angels of God were ascending and descending on it! And behold, The Lord stood above it and said, "I am The Lord, the God of Abraham your father and the God of Isaac; the land on which you lie I will give to you and to your descendants; and your descendants shall be like the dust of the earth, and you shall spread abroad to the west and to the east and to the north and to the south; and by you and your descendants shall all the families of the earth bless themselves. Behold, I am with you and will keep you wherever you go, and will bring you back to this land; for I will not leave you until I have done that of which I have spoken to you." (Genesis 28:10-15 RSV)
"After the death of Moses the servant of The Lord, The Lord [see Rock Of Ages] said to Joshua the son of Nun, Moses' minister, "Moses My servant is dead; now therefore arise, go over this Jordan, you and all this people, into the land which I am giving to them, to the people of Israel. Every place that the sole of your foot will tread upon I have given to you, as I promised to Moses. From the wilderness and this Lebanon as far as the great river, the river Euphrates, all the land of the Hittites to the Great Sea toward the going down of the sun shall be your territory. (Joshua 1:1-4 RSV)
Fact Finder: What did God warn the Israelites would happen (as it is again today with bombings and terrorist attacks committed by people living within Israel's own God-commanded borders) if they did not take complete possession of the land (from Dan to Beersheba, from the Jordan to the Mediterranean, every last square inch) that God commanded them to possess?