This post is using terminology that contributes significantly to common misunderstandings about the region.
Saying that “the population on both sides of that river were 90% Palestinian” is not an accurate description of the ethnic and cultural situation. Palestinian did not have a widely accepted usage as a term describing an ethnic group (and only sorta does now), nor did it have a history as a term describing a country prior to WWII. Prior to WWII the region that makes up the combined area of Israel + Palestine, was under a League of Nations Mandate given to the British, i.e. “British Mandatory Palestine” as it is commonly called. This was the successor government of the region, succeeding the Ottoman Empire.
The term Palestine is akin to the term “Great Britain”, Great Britain as we know is not a country, it is an island, occupied by the countries of Scotland, England and Wales, which are part of the United Kingdom. Palestine is also similar to the term “The Levant”, which is a name referring to a geographic region that does not, and has never, mapped 1:1 to any political boundaries (the Levant is made up of modern day Syria, Lebanon, Israel, Jordan etc.) Since ancient times this spit of land that makes up modern day Israel/Palestine was known as “Palestine”, but there is not a significant history of an ethnic identity linked to this name.
Under the Ottoman Empire it was part of Ottoman Syria, and was divided into three sub-units, the Beirut Vilayet, Syria Vilayet and the Mutasarrifate of Jerusalem. When the British were given League of Nations sanctioned control of the region, they opted to use the well known, especially to Western geographers and writers, historical geographic descriptor “Palestine.”
It should right away be pointed out that Transjordan, which in modern days is known as Jordan, was not part of Mandatory Palestine. So to say Palestinians made up 90% of the population on both sides of the river does not accurately describe the lexical or legal situation prior to WWII. It could be argued that everyone, regardless of ethnic background or religious background, who lived in Mandatory Palestine was a Palestinian–in fact that is precisely what British Mandatory Palestine passports said: British Passport - Palestine.
Across the Jordan river, also a British Protectorate, but not part of Mandatory Palestine, was the Emirate of Transjordan, ruled by Abdullah I bin Al-Hussein, who was a political leader in the Ottoman Empire that had sided with the British during WWI, and was basically rewarded for it–he established the Emirate of Transjordan on his own, and because he had sided with the British during WWI they recognized him as Emir and established a protectorate over his country–which was granted full independence after WWII.
What is more correct to say is that on both sides of the Jordan river, about 90% of the population were Arab, Arab is an ethnic identity, Palestinian largely is not. Historically Arabs thought of themselves primarily in a tribal sense. The origin of the term Arab in fact is tied to being a descendant of one of the original 12 Tribes of the Arabian peninsula (today the term more broadly is often used to refer to anyone whose native tongue is Arabian.) While the original 12 tribes are no longer intact, the Arab world was organized in a tribal way for over a thousand years into modern times. In fact in many Arab communities today tribal affiliations are still of extreme importance, in some Arab countries and regions traditional tribal affiliations have decreased in importance.
Some Jewish extremists will utilize distortions of these facts to imply that modern day Palestinians have no intrinsic right to live in the region because there is no real historical “Palestinian people.” Of course this is not true. The modern day Palestinians, an Arab people, descend directly from Arab peoples who have lived in the region at least a couple hundred years and in many cases probably much longer. The region I give a caveat for that is that a lot of the Palestinian ancestry actually traces back to Bedouin tribes, who were historically nomadic. In fact in late-era Ottoman Palestine there were Arab villages who were part of clans that had still-nomadic Bedouin members, and while they might belong to the same clan they had a bit of disdain for each other, the Bedouins not respecting the villagers giving up the traditional nomadic lifestyle and vice versa. That’s why it gets a little complicated when talk comes to how long someone has been where in this circumstance, but it is generally safe to say “several hundred to at least 1,000 years” depending on who and their specific family tree.
One of the major reasons the Arab world has historically (arguably less so today) been obsessed with the Palestinians interests is precisely because of their shared Arabic ethnicity and culture. There are Arab clans whose membership crosses national boundaries (which were generally not drawn to reflect anything much other than sometimes Ottoman historical boundaries–but the Ottomans did not draw provincial lines based on ethnic communities either.)
Nationalism became a global phenomenon in the second half of the 19th century, and this affected the Ottoman world as well. There was some very nascent, early germinations of a conceptualized Palestinian identity as Palestinian Arabs, distinct from other Arabs, but this was much weaker than the larger pan-Arabism that grew from the nationalist movement.
The real growth in any sort of Palestinian-specific nationalism came during the “troubles” of British Mandatory Palestine, and frankly much of it was driven by a desire to flesh out what it meant to not be a legitimate Palestinian–which specifically meant not being Jewish (there were plenty of Arab Christians in the region back then, less so now but some still remain, and they were in specifically anti-Jewish alliances during Mandatory Palestine.) In the late Ottoman Empire a law was passed providing for basic equality of all Ottoman citizens, albeit still giving Islam a paramount place. Prior to that, there had been a very specific hierarchy in the Ottoman Empire–under the old millet system, specific groups basically governed themselves for most day to day affairs, as long as they remained loyal to the empire and paid their taxes. The top millet were Muslims, and any legal dispute involving a Muslim was settled in a Muslim court. The next highest millet were “Greeks” or the “Roman Millet” as it had been called (this was in reference basically to the conquered peoples of the old Byzantine Empire, who had always referred to themselves as Roman as did their Turkish conquerors), note the Greek Millet was primarily based on practicing Greek Orthodox Christianity, and ignored ethnic realities (there were many Orthodox Christians in this millet who were not Greek, but Greeks had primacy among them in how they were treated in society.) After the Greek millet was the Armenia millet, which was made up of all Christian Armenians regardless of specific religious affiliation (Armenians were historically religiously divided into three different Christian churches.) The lowest millet was that of the Jews. When the Ottomans equalized treatment, it was said that the Greek Orthodox sentiment was “we have been made the same as Jews, we had been fine with Islamic supremacy”, anger at this was part of what lead to the Greek revolutions against Ottoman rule (it certainly was not the only reason, but losing their status as the “privileged minority” in the Empire certainly helped enflame it.)
After the Arab-Jewish Civil War in the final year of the Mandate, and the Arab-Israel War from the 1948 proclamation of Israel (this war technically ended in an armistice, and thus is still ongoing between Israel, Syria and Lebanon–Jordan and Egypt have formally made peace with Israel), at this time a more modern Palestinian identity did begin to develop, specifically because you had effectively stateless Arabs in the Palestine region, who had previously formed now-disempowered nascent civil structures (e.g. the Palestine Arab Congress and other bodies.)
While ultimately it may seem like a quibble, it’s important to understand because the idea that most people on both sides of the Jordan river saw themselves as a specific Palestinian identity is not true, they say themselves as Arabs.
