Privacy

Where do you get the 300,000 figure?

A quick read through Wikipedia showed significantly lower number.

Prior to the Muslim conquest of Palestine (635–640), Palaestina Prima had a population of 700,000, of which around 100,000 were Jews and 30-80,000 were Samaritans,[67] with the remainder being Chalcedonian and Miaphysite Christians.[5][68][69]

The pace of conversion to Islam among the Christian, Jewish, and Samaritan communities in Palestine varied during the early period (638–1098),[70] and opinions vary regarding the extent of Islamization during the early Islamic period.[71] While some argue Palestine was already majority Muslim by the time of arrival of the First Crusade, others contend that Christians were still in the majority and the process of mass adoption of Islam took place only from the 13th century onwards, during the Mamluk period.[71]