The idea that there was a mass migration of Arabs has been heavily fictionalized to give boost to the Zionist narrative that Israel was “a land without a people” before European jewish settlement began in the late 19th century, and that the people who identify as Palestinian really only have roots in the territory that post-dates Zionism (it’s intended to legitimize Israel and de-legitimize the Palestinian claim). The question of land stewardship came up early in the Zionist sources; being European they tended to hold the opinion that nomadic people (as many of the non-coastal residents of pre-mandate Palestine were) did not have a legitimate claim to the land (Sandra Sufjan’s work on the Zionist project to eradicate malaria goes into this quite a bit).

The issue is that there were censuses taken by the Ottomans and the British so we do have a good idea of what the population looked like during the entire period and, while there was expansion, it seems to have largely been through a reduction in infant mortality and improved standards of health rather than immigration from other parts of the region. There was likely some, especially after WWI, but the idea that Palestine was unpopulated and only became so after Jewish settlement began is absurd.

One of the issues with trying to trace by kunya (the place often used as a last name by Arabs) is that there’s no way of telling how recently the ancestor from the place indicated migrated - last week, 50 years ago, 500 years ago? Also the question of whether the individual migrated on his own and married a local woman—in which case are the kids “immigrants” or “locals”? And why would their claim to be “local” be less valid than that of a Jewish family who migrated to Palestine in the early 20th century? You see how complicated this gets rather quickly.

The flip side to this is a historian like Benny Morris, who is pretty accurate about the population of Palestine pre-47 and what happened during the war (he’s also unapologetically Zionist and, in his opinion, the founders should have just displaced everyone during the war of 47-49, and by not doing so they left the door open to all the tensions with the Palestinians that persist). As a historian, I’ve found his work to be solid, and I also appreciate that he’s up front about where he’s coming from, even though I don’t share his political views.

I’ve used James Gelvin’s history of the Israeli-Palestinian conflict in my class and, with the exception of one student who tried to “debunk” him (they managed to miss a whole lot of his actual text while trying to find “clues” to his “agenda”) it’s gone over well with students on both sides of the issue. You might give it a read.