It's the period of time before written records or civilization.
An example of prehistory:
Prehistory refers to the period of human history that occurred before the invention of writing systems, which means that there are no written records or documents from this time. Prehistory covers a vast expanse of time, from the emergence of the earliest humans several million years ago up to the point when written records began, which varied depending on the region of the world. In general, prehistory is divided into three main periods: the Stone Age, the Bronze Age, and the Iron Age. During these periods, humans developed various tools and technologies that enabled them to survive, thrive, and eventually form complex societies. The study of prehistory involves a range of fields, including archaeology, anthropology, and paleontology, and helps us to understand how humans evolved and adapted to changing environments over time.