The accepted assumption is that after the destruction of the Second Temple and the defeat of Bar Kochva, the Land of Israel was emptied of Jews.

When an empire takes over a country, it exiles the élite and leaves the lower classes, and that is what happened after the destruction of both the First Temple and the Second Temple.

[…]

It becomes clear that a significant part of the Arabs [sic] in the Land of Israel are actually descendants of Jews who were forced to convert to Islam over the centuries. There are studies which indicate that 85 percent of this group is of Jewish origin. Some claim that the percentage is less.

[…]

In the Taʻamra tribe territory, there is an ancient Muslim cemetery. Jews who were forced to convert may also be buried here. Some of the graves have a small, sooty niche which testify to the Jewish custom of lighting candles for the souls of the deceased.

And if the war on Gaza were a movie (which unfortunately it is not), this would be the ‘big reveal’ near the end:

To demonstrate how wide the findings are going into the depth Palestinian society we mention here that almost the entire high‐level politicians of the PLO, as well and the majority of Hamas leaders, are of a Jewish origin. This includes Mahmud Abbas (Abu Mazen — a descendant of a family of Rabbis), the late Dr. Saʻeb Erikat, Jibril Rajub (Argov), Maruwan Barguti, Nabil Shaʻat, Khanan Ashrawi, from the Fatah movement, […] Khanin Zuabi, and late sheikh Akhmad Yassin, Ismail Haniʻya, Dr. Mussa Abu Marzuk, Muhammed Def, Dr. Aziz Duwek (a Cohen), and above all Yikhyeh Sinuar from Hamas.

(Emphasis added. Source.)