The Dawn of Mankind
Prehistoric Periods are the earliest stages of human existence. Here's a brief rundown:
Early Sapient (10,000,000 BCE) - Humans first appear on the scene, but they're not exactly what you'd call 'intelligent'. More like 'sapient'.
Olivuviian (2,000,000 BCE) - Humans get a bit more... human. They start making tools and fire. Progress!
Upper Palaeolithic (50,000 BCE) - Humans figure out how to make art. Or, at least, they draw a lot of squiggles on the wall.
And then, well...