If you read about the logistics for large armies in history, before oil-powered transportation was available, it was often an incredible challenge to keep them supplied and fed.
And "large" is not as large as you may imagine, Alexander the Great for instance had maybe 35-40,000 men ... roughly a mid-size sports stadium full of people, but then they would have extra support staff. Every person was a mouth to feed.
Past a certain size and you need more and more people to gather and supply food, so there was a limit to how large of a group of people could be maintained. Add horses or camels and that's yet more mouths to feed.
And they could only be fed by taking from the tows and cities they conquered and travelled through. A very different scenario to travelling through a desert with no supplies.
The bible stories really are fancifully outlandish in their claims.