I believe there were people in the land of Nod. It wasn't too long after Cain went to the land of Nod, banished from the Garden of Eden, where he met his wife. It sure helps explain a lot when just a few hundred years later God has to wipe out an earth which is heavily populated by the nephilim. If you buy the party line about the Creation Story, nothing else will make sense. Adam and Eve were God's creation...the rest of the world had already been created. God's time is not our time....that will also help.