The land we call Ancient Egypt was the narrow strip of fertile land on each side of the River Nile. Where the Nile flows into the Mediterranean Sea it forms a marshy area called the delta, which in Ancient Egyptian times was full of wildlife. This was the Northern boundary of Ancient Egypt. Much further South, upstream, the River Nile flowed through six cataracts, areas of rocks and waterfalls, which made it difficult or impossible to use a boat. The First Cataract was at Aswan, and this formed the Southern boundary of Egypt. The Eastern and Western boundaries of Ancient Egypt were the desert.
From the delta to the First Cataract was more than 1000km but the fertile strip of land on each side of the river was seldom more than a few kilometers wide and all the towns and villages were on the river, so the main way of getting from one town or village to another in Ancient Egypt was by boat. It took about three weeks to travel by boat from one end of Egypt to the other.
The area between the First and Fifth Cataracts is now usually called Nubia, although the Ancient Egyptians called it, among other titles, the Kingdom of Kush. Today Nubia is partly in Egypt and partly in the Republic of the Sudan. Nubia contained lots of gold mines and quarries for the stone needed for building temples, and so the Egyptians tried to conquer or control it, and there were often wars between Egypt and Nubia - sometimes the Egyptians won and sometimes the Nubians won. The Nubians were much darker skinned than the Egyptians which makes it easy to tell the difference between Egyptians and Nubians on Egyptian wall paintings.
Ancient Egypt was divided into two parts: the Southern part was called Upper Egypt and the Northern part, including the delta, Lower Egypt. These names come from the direction in which the River Nile flows, from South to North. The names can be confusing to us because we are used to seeing maps with North at the top, but the Egyptians drew maps to show their country as they would see it looking upstream, with South at the top. So the east bank was on the left and the west bank was on the right. They even used one word to mean both east and left, and of course another word to mean both west and right.
Originally Upper and Lower Egypt had their own Kings. The King of Upper Egypt wore a white crown and the King of Lower Egypt wore a red crown. Then one King of Upper Egypt, whose name was Narmer, became King of both lands. From then onwards the King of Egypt was known as the Ruler of the Two Lands, and often wore a double crown, red and white. When Narmer became Ruler of the Two Lands he took the new name Menes. Menes was the first King of all Egypt and became Ruler of The Two Lands about 2920. Remember that in Ancient Egypt all dates are BCE, so we do not usually need to say so. Remember also that the year 2919 (BCE) comes after the year 2920!
The King of Egypt was an absolute ruler, that is, he had total power over everybody and everything. During the New Kingdom the King of Egypt took the title of Pharaoh (which means Great House in Ancient Egyptian), but today we usually call all the Kings of Ancient Egypt Pharaohs.
We divide what is to many children the most interesting part of Ancient Egyptian history into three Kingdoms, separated by two Intermediate Periods. During the Old, Middle and New Kingdoms most Kings of Egypt ruled in a way which kept stability and order (what the Ancient Egyptians called Ma'at) in the land, but during the First and Second Intermediate Periods the central government was very weak or foreigners ruled the land and Ma'at was absent. Ma'at was very important to the Ancient Egyptians and the female Pharaoh Hatshepsut was accepted as King (she never used the title Queen) because during her reign Ma'at was present.
In 332 Alexander the Great conquered Egypt and Egypt became just a part of the Empire of the Greeks