This period corresponds to the Late Neolithic (Stone Age), and covers the cultural and social changes which occurred between the late Palaeolithic period (hunter gatherers)and the early Pharaonic era (the Early Dynastic Period). During the Predynastic Period Egyptians developed a written language (centuries before writing was developed in Mesopotamia) and an institutionalised religion. They developed a settled, agricultural civilization along the fertile, dark soils (kemet or black lands) of the Nile (which involved the revolutionary use of the plough) during a period in which Northern Africa was becoming more arid and the edges of the Western (and Saharan) desert (the deshret or red lands) spread.
Although archaeologists know that writing first emerged during the Predynastic Period, very few examples still exist today. What is known about the period comes from remains of its art and architecture.
The Predynastic Period is divided into four separate phases: the Early Predynastic which ranges from the 6th to 5th millennium BCE (approximately 5500 - 4000 BCE), the Old Predynastic which ranges form 4500 to 3500 BCE (the time overlap is due to diversity along the length of the Nile), the Middle Predynastic which roughly goes form 3500 - 3200 BCE, and the Late Predynastic which takes us up to the First Dynasty at around 3100 BCE. The reducing size of the phases can be taken as an example of how social and scientific development was accelerating.
The Early Predynastic is otherwise known as the Badrian Phase -- named for the el-Badari region, and the Hammamia site in particular, of Upper Egypt. The equivalent Lower Egypt sites are found at Fayum (the Fayum A encampments) which are considered to be the first agricultural settlements in Egypt, and at Merimda Beni Salama. During this phase pottery was being made, often with quite sophisticated designs ( a fine polished red wear with blackened tops), and tombs were constructed from mud brick. Corpses were merely wrapped in animal hides.
The Old Predynastic is also known as the Amratian or Naqada I Phase -- named for the Naqada site found near the centre of the huge bend in the Nile, north of Luxor. A number of cemeteries have been discovered in Upper Egypt, as well as a rectangular house at Hierakonpolis, and further examples of clay pottery - most notably terracotta sculptures. In Lower Egypt, similar cemeteries and structures have been excavated at Merimda Beni Salama and at el-Omari (south of Cairo).
The Middle Predynastic is also known as the Gerzean Phase -- named for Darb el-Gerza on the Nile to the east of Fayum in Lower Egypt. It is also known as the Naqada II Phase for similar sites in Upper Egypt once again found around Naqada. Of particular importance is a Gerzean religious structure, a temple, found at Hierakonpolis which had early examples of Egyptian tomb painting. Pottery from this phase is often decorated with depictions of birds and animals as well as more abstracted symbols for gods. The tombs are often quite substantial, with several chambers built out of mud bricks.
The Late Predynastic, which blends into the 1st Dynastic Period, is also known as the Protodynistic phase. Egypt's population had grown considerably and there were substantial communities along the Nile which were politically and economically aware of each other. Goods were exchanged and a common language spoken. It was during this phase that the process of wider political agglomeration began (archaeologists keep pushing back the date as more discoveries are made) and the more successful communities extended their spheres of influence in include nearby settlements. The process led to the development of two distinct kingdoms of Upper and Lower Egypt, the Nile Valley and Nile Delta areas respectively.