I insist that you state clearly what region you are describing as "Palestine" in the above statement, and cite your source for the population figure you claim.
The British census of Palestine of 1922 shows 752,048. Of that number 83,790 were Jews.
You can get Ottoman census data from the late 19th century. In 1878 the Turks counted 462,465 people, 15,011 of them Jews.
To my knowledge, there is no data available on population figures immediately prior to 1917, when the British took over, but it cannot have changed much from 1917 to 1922, so around 700,000 is a good estimate. Clearly the population did not increase by 300,000 people in 5 years.
Anyway, even if we stick to the Ottoman number, 450,000 souls may be sparesly populated, but it is not unihabited.
Turkish and British census data for these years are readily available.