Ideas such as the Khazar theory of Jewish origin are making the rounds again. The Khazar theory posits that Ashkenazi Jews are primarily descendent from Khazar converts to Judaism. The Khazar Khaganate was an early medieval central Asian state that converted to Judaism in the 8th century CE. There are many problems with this theory. Primarily, the historical evidence for the conversion of the Khazars is extremely limited. The singular primary source for this event, namely a letter that was supposedly sent by a "King Joseph" of the Khazars to Hasdai ibn Shaprut, the Jewish foreign minister of Abd ar-Rahman III, Kalif of Andalusia. Though it is certain that Hasdai believed there to be a Jewish Khazar state, and he most likely tried to send them a letter, the letter that is traditionally considered to be the response is very suspect. Forgeries of this kind abounded during the Middle Ages.
Jews during this era were stateless in a moment when the Christian and Muslim worlds seemed to united against each other. There was a general idea that a secret Jewish kingdom would arise to retake Jerusalem and usher in the Messianic era. A Jewish traveler who went by Eldad ha-Dani famously claimed that there was a hidden kingdom of the 10 lost tribes in East Africa. The letter from King Joseph of the Khazars fits right into this era of global travelers claiming to have found Jewish kingdoms. Some archeological evidence suggests that there were some Jew in the Caucuses during this era. It is possible that some of the Khazar nobility converted to Judaism as a middle-ground monotheistic religion that allowed them to stay neutral in the global dichotomy of Christianity and Islam. There is not nearly enough evidence to suggest that there were enough Khazar converts to be the primary ancestor population of Ashkenazi Jews.
Anyone who has studied the historical record knows that there were already large Jewish population centers in Europe when the Khazars were supposed to have converted. This theory has to ignore so much of established historical fact that it feels ridiculous to have to refute. Despite this, most people have little idea of how history is studied and just assume that if this idea is written about, it must be true.
The Khazar theory is helpful for people who seek to delegitimize Zionism. It allows them to form a category of illegitimate nationalisms that have no good reason to exist. Accepting the Khazar theory as a good model of Jewish heritage, the Jews have no reason to live in Palestine, since they are actually from central Asia. This is unlike the indigenous Palestinians, who have lived in Palestine since time immemorial. The Khazar theory itself fails to account for anyone who isn't a descendent of Eastern Ashkenazi Jews. Part of the original impetus for the Khazar theory was that the pre-WWII Eastern European Jewish population had grown so fast during the early modern period that some anthropologists were skeptical that they were really fully descendent of the western European Jewish migrants. Instead, the large population increase was due to the assimilation of many unknown central Asian Jews who they imagined migrated to the Kingdom of Poland en-masse. This theory was, and remains, fully European centric. In its origin context, it allowed western Europeans to respect the emancipation and integration of western European Jews, as they were true "Semites" and civilized, whereas the Eastern European Jews were fit to hate because they were primarily uncivilized barbarians of the central Asian Steppe. This also likely formed an associated with "invading" Eastern European Jewish migrants with the medieval Mongol hordes. Much in the same way that in the US, people like to label the Latin American immigrants as criminals and rapists.
The Khazar theory does not account for the ancestry of Mediterranean, West, Central, and South Asian Jewish populations that participated in Zionism.
It is legitimate to differentiate between the Jewish Zionists and the indigenous Palestinians. The vast, vast majority of the Jews who live in Israel are descendants of immigrants who came in the last century through Zionism. Many immigrants choose to change their names. In Israel, where modern-Hebrew was imposed as the national Jewish language, many families from all over the diaspora chose to change their last names to Hebrew equivalents under this cultural pressure. You find Eastern European Jews changing their names from Greun to ben-Gurion, or west Asian Jews changing their name from Abdullah to Ovadiah. You can find people online referring to Bibi by his ancestors' Polish last name, in an effort to highlight his immigrant Jewish heritage.
The implication is that the immigration reflects an illegitimate nationalism or illegitimate existence in the land. I want to address each of these thoughts independently.
Nationalism is always fabricated and made up. Political historians generally look to the French revolution for the origins of modern political thought, since that revolution really had it all. The idea of nationalism was expressed for the first time during this revolution. Previously, the leaders of a country imagined that they themselves embodied the government. The French revolutionaries adapted the ideas of social contract theory to mean that the French people, the nation, together held the power of French governance. In many ways the "French nation" was a fiction. The people who lived in France were determined by the borders drawn during the Monarchical period. The borders during the revolution had been drawn at the peace of Westphalia. In order to argue for the reality of the French people, the government began to impose of Parisian French as the true French language in order to create a common language for the people of France. Similarly, a national culture for France had to be developed. This manufactured unity of the French people was a powerful narrative that sought to unite them under a democratic political system.
Not everyone who lived in the borders of France was immediately considered part of the French nation. The Jews of Alsace had to fight pretty hard to get nominally equal French citizenship, since it was not immediately granted when the revolutionary government formed. On one hand, nationalism can be used to liberate a people from an oppressive government that does not represent them, but it also necessarily excludes people and provides a new medium for discrimination. The Jews of Alsace were seen as foreigners who did not belong in the already complete French nation. Already built nation states tend to be stable enough to critique themselves and tolerate immigrants. This generally manifests in people arguing that immigrants can assimilate in the national culture or the nation can be multi-cultural. Generally, the prevalence of these ideas lead to more tolerance of immigrants, which is a good thing.
Palestinian nationalism is foundationally as false as any other nationalism. I hope that people understand that when they critique Zionism in the same way. However, Palestinian nationalism is rightly deserving of our favor, since it is in the "fighting oppressive government" stage. Palestinian nationalism also has an "other," a group that is definitely not part of it. Those are the Zionist Jews. Though in theory, many claim they happily embrace non-Zionist Jews, in practice anti-Zionist regimes have ended up just discriminating against Jews in general. To be fair, there is much to hate about what Zionism does to a Jewish community. The transformation of religion into nationalism is not pretty. Unfortunately, most religious community in the world today possess elements of religious nationalism. We still live in the era of Ethno-Nationalism, and its popularity shows no signs of waning. Any discrimination against religious-Nationalism will lead to increased government oversight of the religious community, which if not distributed equally, will manifest as religious discrimination. Also it is almost impossible to destroy ideas directly, they generally need to be superseded by more popular ideas.
Regarding immigration. Most of the Jews who live in Israel today are descendants of immigrants who came in the last century. Under Zionist direction, many of them have participated in the Zionist settler colonial process. Small amounts of Jewish immigration to the region has existed for centuries. Following the first crusade, when the historic Palestinian Jewish community was mostly wiped out, diaspora Jews began constituting the majority of Palestine's Jewish community. By the early modern period, there were sizable Jewish populations in the Jerusalem, Safed, Tiberias, and Hebron. In 19th century, the majority of the Jews living in these areas were of Spanish Jewish descent, most of them were settled in the region by the Ottoman empire after they were expelled from Spain the 1492. A minority of them were immigrants from eastern Europe, and an even smaller minority were descendants of the indigenous Jewish population.
With the increasing popularity of Zionism at the turn of the 20th century, more Jews began to immigrate to Palestine with the intention of colonizing it. In Palestine, at the time, the majority of the people living there were peasant farmers who rented from large landowners, in a feudal system of farming. The Zionists bought land from these large landowners and then evicted the native Palestinian peasants. This was effectively the start of tensions between indigenous Palestinians and Jewish immigrants. Indigenous Palestinian violence against the Zionist settlers was stoked by preachers like Izz ad-Din al-Qassam, who framed the Jewish immigrants within an Islamic context, weaponizing Islamic antisemitism against the Jewish colonizers.
Anti-colonial resistance is a legitimate cause, but the anti-colonial activity of the area, took on an antisemitic character which threatened even the Jews who were not participating the in the colonial activity. Continuously increasing tensions.
Foreign supporters of Palestinian liberation, who don't consider themselves antisemites, cannot be in favor of expelling the "foreign Jewish population" of Palestine. It is difficult to determine if people who believe in a liberated Palestinian state will be tolerant of a large Jewish population in the territory. The militant Palestinian liberation groups like Hamas and Hezbollah tend to believe that the Jews will emigrate out of fear once they achieve enough regional power. This mass emigration is unlikely to happen. The idea is based on the narrative of the wandering Jew who flees danger. Even though some Jews may leave, I find it unlikely that it will happen on the scale that they imagine. Other Arab states, like Yemen and Iraq have undergone processes like this, but they were only successful because Israel was willing to absorb so many Jewish immigrants. All the countries that attempted this before the state of Israel was created generally failed to induce a mass emigration of their Jewish populations.
Those who fantasize about a mass emigration of their perceived enemies tend to be supportive of those enemies' extermination if they won't leave. We are seeing this right now with Israel. The most fascistic Zionists within Israel, especially the followers of Meir Kahane, fantasized about a mass emigration of Arabs from Israel. Kahane proposed bribing them all to leave, but they really wanted to them to leave out of fear. This fear tactic was first implemented with some success during the 1948 war, when about 800,000 Palestinian Arabs fled their homes in Israel out of fear and were never allowed to return.
The fact of the matter is, 7 million Jews live in Israel today. Though the land they live upon was acquired in bloodshed, getting rid of them will required even more bloodshed. The best peace solution is not to return to the fantasy of a pre-Zionist independent Palestine. It's as impossible as the Zionist fantasy to return to a pre-Roman independent mono-cultural Judea. Decades of immigration, expulsion, and blood has irrevocably scarred the region.
My own fantasy is for a singular secular state that recognizes the religious and national identities that it contains. This state would also offer reparations to victims of the violence. Even though these reparations will be offered to Israelis who lost family and property in the violence, the vast majority of the recipients will be Palestinians who live both domestically and abroad, since they make up the vast majority of victims of the violence over the past century. I fear that such a state will be far too unstable to maintain itself. Maybe it could create a unifying peace narrative, but there will be significant pockets of Zionists who would want to maintain Jewish supremacy and the "right to return" for Jews globally. On the other side, there will be Palestinian Islamic nationalists who would want to start forcing Jews out of the country. The history of violence would encourage people to take up arms once again.
Another possible solution, which is supported by the international community, is the two state solution. This is an old idea that dates back to the British mandate period. It has always been a messy solution, since the population distributions within historic Palestine do not lend well to simple divisions. In spite of the border drawing difficulties, two states would allow for the national expression of both groups. The very small territory would require them to cooperate very closely with each other, though there remains the great worry of violence re-erupting should extremists come to power on either side.
I don't know which solution would ultimately work the best. I do know that we must be thinking pragmatically about how to accommodate a peaceful coexistence of both groups in the land without fantasizing about the extermination of one or the other. As long as our discourse tolerates such ideologies, it will be very difficult to reach a lasting peace agreement.