Do you have to argue that point or is that th eone your picking? You could talk about how all of Egypt being centered in a river valley making it easier for the monarchy to control its people and restrict the power of minor nobles and aristocracy. Egypt also has a perfect setting alowing the exchange of ideas with other civilizations but through narrow channels thus giving the king a much easier time of taxing trade.
Especially talk about Ramses II (the great) as an example of state propoganda. he said he won the battle of Qadesh (it was a draw) and he and every other pharoah claimed godhood and obedience from them. One of the reasons people though Ramses was so great was that he SAIS he was great. Ingenious.