I don't entirely understand. Gaza and the West Bank weren't feudal societies before 1967. There has been a good deal of work on the class structures in Palestine during the Mandate. A quick search threw up:
Arab Labor In Mandate Palestine - The Emergence of a Working Class (Interactive Encyclopedia of the Palestine Question)
Those 'demographic economic and social changes' included Jewish immigration and the development of a specific Jewish capitalist sector in addition to the smaller Palestinian capitalist sector, but the overarching catalyst was British imperialism.
(There are other related articles at that site). See also the PDF attached below Talal Asad (1976). Class Transformation under the Mandate.
The occupation of Gaza and the West Bank in 1967 significantly changed the situation and proportions of the different classes in them but it didn't initiate their creation. See for example Hilal, J. (1976). Class Transformation in the West Bank and Gaza - PDF attached below
This has a section about proletarianization after 1967, but it's not about people being forced off the land and into wage labour (a process which had already begun significantly under the Mandate) but the changed status of sections of the middle classes
An interesting article about the development of the Palestinian middle classes. Itamar Radal - The Rise and Fall of the Palestinian-Arab Middle Class Under the British Mandate, 1920-39 (2016) PDF attached below