“For me, a screenplay starts with something I can tell other people in five minutes. If you’re pitching a movie and it takes longer than five minutes, there’s something wrong. That economy seems to have really worked for me. The more detail I include in my pitch, the more other people’s and my own eyes start to glaze over.”
– Harold Ramis (Ghost Busters, Back to School)
Depends how much time you have and your status. Steven Spielberg can take as long as he likes. A newbie has less time. The best pitches will align with the hero's journey: http://www.clickok.co.uk/index4.html
The Sumerians are the story around 4000 a. C., although they have existed for some time before that date.
Harley Parts