What geographic conditions favored the establishment of large states north of the first cataract of the nile river?

The geography played a big role in the establishing of the states and so is the case with the countries of North Africa and their size. This is due to multiple geographic reasons, the natural resources are obscure, there's very small amount of freshwater available, the landscape is dominated by deserts, and because of these factors there was a relatively small population on very large areas. This all contributed to the creation of large countries where people were mostly concentrated in very small area of the country.