Conventionally, History starts with written records. Everything that came before is prehistoric. It’s useful as a concept when discussion groups of humans in the last 10-odd millennia, but not really for things that are a couple of millions years old.
> Prehistory [...] is the period of _human_ history between the first known use of stone tools by hominins c. 3.3 million years ago and the beginning of recorded history with the invention of writing systems.
Yes, you are right. I was thinking in the context of human populations. And then there is the question of what is human and what is not, and the limit between archaeology and paleontology when considering homininae.
I suppose you are actually talking of a time preceding prehistory by a fair lot!