C.C. McCown offers estimate of Palestine population.
C.C. McCown, "The Density of Population in Ancient Palestine," Journal of Biblical Literature (December 1947): 436
With the Jewish population in the Decapolis, the Shephelah, and the coastal cities, the total would fall below, rather than above Harnack's estimate of 500,000. The total population of western Palestine would fall far under 1,000,000.