Prehistory is what historians call the period before people learned to write. In the case of Britain it means everything before the Romans. Most of the past, in fact
In prehistory, it is very difficult to be exact about dates. The periods of time you deal with are so big, academics give them names. No one then thought in this way.
- Palaeolithic = Old Stone Age 250,000 to 8000BC
- Mesolithic = Middle Stone Age 8000 to 4300BC
- Neolithic = New Stone Age 4300 to 2300BC
- Bronze Age 2300BC to 600BC
- Iron Age 600BC until the Romans
Remember, the boundaries between each period are very flexible especially during academic discussion. They also vary depending on what part of the world you choose.
Things did not suddenly shift gear in 8000BC, 4300BC, 2300BC or 600BC. Much as things didn't change on January 1st 2000.