Victor Sharpe's interesting discussion of Gaza's history omits any discussion of the impact of its brutal jihad conquest for the native vanquished Jewish (and Samaritan) and Christian populations, or the chronic, oppressive imposition of dhimmitude in all of historical Palestine, including Gaza, during more than 13 centuries of Muslim occupation. For additional analysis about the historical plight of the subjugated dhimmis, see this essay at The American Thinker, both parts 1 and 2. Below are some relevant details about the initial Muslim conquest and colonization.
Moshe Gil's monumental study of Muslim subjugation and rule of historical Palestine (from 634-1099 CE) elaborates on the initial wave of jihad conquests (during the fourth and fifth decades of the seventh century, CE), and details the lasting destruction they wrought (cited in my The Legacy of Islamic Antisemitism, pp. 79-80 )
...at the time of the conquest, Palestine was inhabited by Jews and Christians....The Arab tribes were to be found in the border areas, in keeping with arrangements made with the Byzantine rulers....one can assume that the local population suffered immensely during the course of the war [i.e., jihad conquests] and it is very likely that many villages were destroyed and uprooted in the frontier regions, and that the lot of these local populations was very bitter indeed. It appears that the period of the conquest was also that of the destruction of the synagogues and churches of the Byzantine era, remnants of which have been unearthed in our own time and are still being discovered. The assumption is based both on what is said in a few Christian sources...and on Muslim sources describing ‘Umar's [Umar b. al-Khattab] visits to al-Sham. There is no doubt that one of the main purposes of these visits was to establish order and put an end to the devastation and slaughter of the local population...Towns in the western strip and the central strip (the region of the red sand hills and the swamps) in the Sharon, decreased from fifty-eight to seventeen ! It is estimated that the erosion of the soil from the western slopes of the Judaean mountains reached - as a result of the agricultural uprooting during the Muslim period - the gigantic extent of 2,000 to 4,000 cubic meters....We find direct evidence of the destruction of agriculture and the desertion of the villages in the fact that the papyri of Nessana are completely discontinued after the year 700. One can assume that at the time the inhabitants abandoned the place, evidently because of the inter-tribal warfare among the Arabs which completely undermined the internal security of the area.
Moreover, with regard to the conquest of Gaza, specifically, the Muslim chronicler Baladhuri maintained (The Legacy of Islamic Antisemitism, p.79) that 30,000 Samaritans and 20,000 Jews lived in Caesarea alone just prior to the Arab Muslim conquest; afterward, all evidence of them disappears.