Responding to a Debate in the Comments:
A couple of years ago a Jewish relative of mine returned from a trip to Israel filled with enthusiasm for the country and its accomplishments. We fell to discussing the Palestinian question and she explained to me that the Arabs there were mostly immigrants, and that the country had been almost unoccupied when the Zionists started arriving.
This seemed implausible to me - a fertile country, a stone's throw from the origins of early civilization, unoccupied and uncultivated. I started researching the question, and it quickly became clear that this had to be nonsense.
In 1944, for example, the British survey found that 90% or more of the land was owned by Arabs, who produced an even larger proportion of the agricultural production. The notion that the land was unpopulated is also belied by the statistics;
From census data:
The Ottoman census of 1878 for Jerusalem, Acre, and Nablus showed 400,000 Muslims, 43,000 Christians, and 25,000 Jews, of whom 10,000 were foreign born. Thirty-two years later, the demographic of Jerusalem considered by itself had become predominantly Jewish - though the numbers are still small compared to the whole district's population of 1878.
The short version is that Israel had a large population, mostly Muslim, with a significant minority of Christians and many fewer Jews around 1900. Jewish immigration during the first half of the twentieth century, and expulsion of Arabs in 1948 largely reversed these population proportions.
After a visit to Palestine in 1891, Ahad Ha'am wrote:From abroad, we are accustomed to believe that Eretz Israel is presently almost totally desolate, an uncultivated desert, and that anyone wishing to buy land there can come and buy all he wants. But in truth it is not so. In the entire land, it is hard to find tillable land that is not already tilled; only sandy fields or stony hills, suitable at best for planting trees or vines and, even that after considerable work and expense in clearing and preparing them- only these remain unworked. ... Many of our people who came to buy land have been in Eretz Israel for months, and have toured its length and width, without finding what they seek.
There is also genetic evidence that the Palestinians have long been in Israel. That genetic evidence indicated that in many ways Israelis and Palestinians are more closely related that Palestinians and some other Arab groups - that "Dad was out and about, while Mom stayed home" as Judy Siegel-Itzkovich put it in The Jerusalem Post. A potful of studies here. The Jews who stayed in Palestine mostly converted to Christianity and later to Islam.