Palestine has never existed . . . as an autonomous entity. There is no language known as Palestinian. There is no distinct Palestinian culture. There has never been a land known as Palestine governed by Palestinians. Palestinians are Arabs, indistinguishable from Jordanians (another recent invention), Syrians, Lebanese, Iraqis, etc.
The word itself derives from "Peleshet", a name that appears frequently in the Bible and has come into English as "Philistine". Philistines was migrant people from the Aegean Sea and the Greek Islands who settled on the southern coast of the land of Canaan. There they established five independent city-states (including Gaza) on a narrow strip of land known as Philistia. The Greeks and Romans called it "Palastina".
The Philistines were not Arabs, they were not Semites. They had no connection, ethnic, linguistic or historical with Arabia or Arabs. The name "Falastin" that Arabs today use for "Palestine" is not an Arabic name. It is the Arab pronunciation of the Greco-Roman "Palastina" derived from the Peleshet.
In the First Century CE, the Romans crushed the independent kingdom of Judea. After the failed rebellion of Bar Kokhba in the Second Century CE, the Roman Emperor Hadrian determined to wipe out the identity of Israel-Judah-Judea. Therefore, he took the name Palastina and imposed it on all the Land of Israel. At the same time, he changed the name of Jerusalem to Aelia Capitolina.
After the Roman conquest of Judea, "Palastina" became a province of the pagan Roman Empire and then of the Christian Byzantine Empire, and very briefly of the Zoroastrian Persian Empire. In 638 CE, an Arab-Muslim Caliph took Palastina away from the Byzantine Empire and made it part of an Arab-Muslim Empire. The Arabs, who had no name of their own for this region, adopted the Greco-Roman name Palastina, that they pronounced "Falastin".
During the First World War, the British took Palestine from the Ottoman Turks. At the end of the war, the Ottoman Empire collapsed and among its subject provinces "Palestine" was assigned to the British, to govern temporarily as a mandate from the League of Nations.
The Balfour Declaration of 1917, confirmed by the League of Nations Mandate, commited the British Government to the principle that "His Majesty's government view with favour the establishment in Palestine of a Jewish National Home, and will use their best endeavors to facilitate the achievement of this object. . . . " It was specified both that this area be open to "close Jewish settlement" and that the rights of all inhabitants already in the country be preserved and protected.
During the period of the Mandate, it was the Jewish population that was known as "Palestinians" including those who served in the British Army in World War II.
The current myth is that these Arabs were long established in Palestine, until the Jews came and "displaced" them. The fact is, that recent Arab immigration into Palestine "displaced" the Jews. That the massive increase in Arab population was very recent is attested by the ruling of the United Nations: That any Arab who had lived in Palestine for two years and then left in 1948 qualifies as a "Palestinian refugees". After the 1967 war this was changed to "Israeli refugees.
What was to become of "Palestine" after the Mandate? This question was taken up by various British and international commissions and other bodies, culminating with the United Nations in 1947. By 1948, the Arabs had still not yet discovered their ancient nation of Falastin. When they were offered half of Palestine west of the Jordan River for a state, the offer was violently rejected. Six Arab states launched a war of annihilation against the nascent State of Israel. Their purpose was not to establish an independent Falastin. Their aim was to partition western Palestine amongst themselves.
They did not succeed in killing Israel, but Trans-Jordan succeeded in taking Judea and Samaria (West Bank) and East Jerusalem, killing or driving out all the Jews who had lived in those places, and banning Jews of all nations from Jewish holy places. Egypt succeeded in taking the Gaza Strip. These two Arab states held these lands until 1967. Then they launched another war of annihilation against Israel, and in consequence lost the lands they had taken by war in 1948. During those 19 years, 1948-1967, Jordan and Egypt never offered to surrendar those lands to make up an independent state of Falastin. The "Palestinians" never sought it. Nobody in the world ever suggested it,much less demanded it.