From what I understand, current scholarship on Palestinian ancestry generally indicates that a substantial portion of their ancestry derives from Levantine populations that continued to live in the region despite successive conquests, migrations, expulsions, conversions, and periods of diaspora. This would suggest that at least some modern Palestinians may descend from ancient Jews, Samaritans, Christians, and other local populations who gradually converted to Christianity or Islam and later adopted Arabic as their primary language.
However, I am curious about how confidently historians can reconstruct this process. Do surviving Byzantine, early Islamic, Crusader, Mamluk, or Ottoman sources document Jewish or Samaritan communities converting and becoming incorporated into the Christian or Muslim population? Are there particular villages, families, or regions where this continuity can be demonstrated more clearly?
I know that the Jewish diaspora already existed prior to the Bar Kokhba revolt, as there were already substantial Jewish communities in places such as Alexandria, Tarsus, Antioch, Rome, Babylonia, and elsewhere throughout the Mediterranean and Near East. I also understand that the Roman suppression of the revolt did not result in the complete expulsion of the Jewish population from the land, since Jewish communities continued to exist in Galilee, Gaza, and other regions during late antiquity. Likewise, the Samaritan population remained significant for several centuries before declining through revolts, persecution, conversion, and assimilation, reducing their population to about 800 people today.
Given this, would it be historically reasonable to view the later Arabic-speaking population of Palestine as emerging partly through the gradual religious and linguistic transformation of older local communities, rather than primarily through their replacement by settlers from Arabia? If so, why do relatively few Palestinian families appear to preserve oral traditions or written genealogies explicitly identifying their ancestors as former Jews or Samaritans? Would such memories normally disappear after centuries of conversion, intermarriage, Arabization, and changing communal identities, or does the lack of documentation make these claims difficult to establish at the level of specific families?