According to Numbers 1:46, the Israelite army stood at “six hundred three thousand five hundred fifty.”
On the basis of the census taken, one must assume there was an excess of 2,000,000 Israelites in the wilderness, of which 603,550 were soldiers. The sheer numbers raises many questions: How could the wilderness provide for such a large number of people over a forty year period? By the same token, how could the livestock and other flock animals subsist on a relatively sparse and uncultivated terrain? When one considers the amount of time the Israelites stayed in Kadesh-Barnea, there would have been ample archeological evidence indicating the presence of a large population having once lived there, yet no such evidence has yet been unearthed.
Moreover, if the Israelite nation numbers were indeed in excess of 2,500,000, as one scholar noted “The reader can figure that two and a half million people marching in an old-fashioned column of fours would extend some 350 miles!” Along these lines, if the Israelites were 2,500,000 in size, they would never have been able to logistically cross the Sea of Reeds in one night. In fact, it probably would have taken several weeks to cross that body of water.
No ancient people in antiquity ever amassed an army of that size, with the possible exception of China. One of the most successful conquerors Sargon of Akkad (ca. 2350 B.C.E.), was proud of the fact he had a standing army garrisoned in his palace nearby for his immediate use. In the famous battle of Qadesh between Egypt and the Hittites, the Hittites had an army of some 40,000, the largest army ever assembled in the ancient world, with an army of 20,000 men, the Egyptian army was barely able to win a stalemate. Shamshi-Adad (1800 B.C.E, Assyria) claimed to have amassed an army of 60,000 for the siege of Nurrugum. If Israel really had a fighting force of 603,550, they would have never have feared a handful of Egyptian, Amalekites, whose military outcome remained uncertain as long as Moses kept his arms raised. Nor would the Israelites have had much to fear the Canaanites whose entire population did not exceed at the very most 1,000,000 people during the Late Bronze Age.
Another one of the great battles of antiquity, which took place at Qarqar (Phoenicia) between a coalition of twelve kings from Palestine-Syria (including King Ahab) against the Assyrians, had 72,000 men in that coalition, according to the Annals of Shalmaneser III (ANET, 278). Ahab contributed 2,000 chariots and 10,000 soldiers. Here too, ancient warfare did not involve larger numbers than that, hence the 603,550 does not seem like a realistic or likely number for an army.
Internal evidence from the Torah must make one think twice about the accuracy of our assumption that eleph means “thousand. The Torah clearly indicates that Israel was quite small, especially compared to its neighbors (see for examples Exod. 23:29–30; Deut. 7:7, 22). Furthermore, the Torah then declares that Moses and Aaron judged the entire nation, until implementing Jethro’s pragmatic advice – all of which suggests that the nation could not have been that enormous in size.
In terms of practical daily logistics, the size of the camp of the Israelites have posed considerable waste management problems (both for themselves and for their animals), presenting a real bio-hazzard for those encamped in close quarters. Remember: the Israelites did not enjoy the benefit of modern plumbing! In one settlement, Kadesh Barnea, the Israelites lived for 38 years (Deut. 1:46), there would most certainly be some strong archaeological evidence of such a large population (where an entire older generation died) having once lived there. The physical evidence is still lacking.