Ancient Egypt was an ancient civilization of eastern North Africa, concentrated along the Northern reaches of the Nile River in Egypt. The civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh, and it developed over the next three millennia. Its history occurred in a series of stable Kingdoms, separated by periods of relative instability known as Intermediate Periods. Ancient Egypt reached its pinnacle during the New Kingdom, after which it entered a period of slow decline. Egypt was conquered by a succession of foreign powers in this late period, and the rule of the pharaohs officially ended in 31 BC when the early Roman Empire conquered Egypt and made it a province. Although the Egyptian military forces in the Old and Middle kingdoms were well maintained, the new form that emerged in the New Kingdom showed the state becoming more organized to serve its needs.
For most parts of its long history, ancient Egypt was unified under one government. The main military concern for the nation was to keep enemies out. The arid plains they wanted to get rid of and deserts surrounding Egypt were inhabited by nomadic tribes who occasionally tried to raid or settle in the fertile Nile river valley. Nevertheless, the great expanses of the desert formed a barrier that protected the river valley and was almost impossible for massive armies to cross. The Egyptians built fortresses and outposts along the borders east and west of the Nile Delta, in the Eastern Desert, and in Nubia to the south. Small garrisons could prevent minor incursions, but if a large force was detected a message was sent for the main army corps. Most Egyptian cities lacked city walls and other defenses.
The history of ancient Egypt is divided into three kingdoms and two intermediate periods. During the three Kingdoms Egypt was unified under one government. During the Intermediate periods (the periods of time between Kingdoms) government control was in the hands of the various nomes (provinces within Egypt) and various foreigners. The geography of Egypt served to isolate the country and allowed it to thrive. This circumstance set the stage for many of Egypt's military conquests. They enfeebled their enemies by using small projectile weapons, like bows and arrows. They also had chariots which they used to charge at the enemy.