As you might have guessed, the geography of ancient Egypt is all about the Nile. The ancient Egyptians depended on the river for their survival, and till now the bulk of the population lives along its banks.
But in fact, it wasn't always that way. Before the days of the Pharaohs, before 5000 BC, the majority of the land was actually full of vegetation and wild animals.
There was no need at that time to settle near the Nile. The numerous hunter-gatherer tribes travelled around nomadically following wild animals. They were of different ethnicities and origins.
But then around 5000 BC the lush green began to turn into desert. The climate changed and started drying out, and thus the animals began to migrate elsewhere. This forced the tribes to settle nearer and nearer to the Nile river since it started becoming the main source of fresh water in Egypt.
Slowly the tribes began to combine and form societies, which then became the beginning of an integrated Egypt.
The two main areas of Egypt (north and south) had some distinct features that would tell them apart:
The people of the north (Lower Egypt) had their origins in the near east, and thus had lighter skin and straighter hair.
The people of the south (Upper Egypt) had their origins in Nubia, and thus had darker skin and curlier hair.
Then in 3100 BC, King Narmer unified the land and started the Pharaonic dynastic period. The geography of ancient Egypt changed and became that of one country...
Although modern day Egypt is even more integrated, and had many invasions from different cultures, the distinction could still be seen. The features, accents and customs of the Upper Egyptians differ from those of the Lower Egyptians.
Before the Old Kingdom and the dynasties were established, during what's called the pre-dynastic period (before 3100 BC), there were no capital cities.
There were some areas though that could be considered centers of settlements and tombs. These areas are Abydos, Hierakonpolis, and Naqada. Graves, temples and artifacts were found in these areas by the thousands.
Once the land was unified and the Old Kingdom began, Egypt began to have a series of capital cities.
The funny thing about Egyptian capitals is that there were often two at the same time - One administrative (where the political business was conducted) and one religious (where major temples and cults conducted their rituals).
This reflects the belief the Egyptians had that it was the king's responsibility not only to rule the land, but also to intermediate with the Gods for the sake of the people and the country.
Until the establishment of Alexandria by Alexander the Great in 331 BC, the following were the two most important cities of Egypt during the Pharaonic period:
Memphis: The first proper administrative capital of the Old Kingdom, after the rulers stopped using the above 3 centers as capitals in 3100 BC.
It's near modern Cairo and its ruins now lie in modern-day Sakkara, Dahshur, Abusir, and Giza. The Egyptian name was actually Ineb Hedj, Memphis is the Greek name for the city.
Memphis was chosen for its strategic location between Upper and Lower Egypt to ensure political control and control of the trade between the two divisions.
Thebes: Situated where modern day Luxor now is, this was the religious capital during much of the New Kingdom. It was called Niwt in ancient Egyptian.
The area now boasts some of the world's most beautiful ancient temples, such as the Karnak and Luxor temples. It was home to an extremely powerful religious cult, that of the God Amun.
Thebes also contains the Valley of the Kings and Valley of the Queens, with hundreds of grave sites.
Of course there were other capital cities but they were very short-lived compared to these main two.
Although the actual population of ancient Egyptians wasn't recorded until the Romans took over, there are some scientific estimates that are based on the geography of ancient Egypt and its capacity to support agriculture: