As I mentioned earlier, even colonies in a much more modern technological age (eg, Jamestown, Plymouth, and Roanoke) were usually on the order of a hundred people or so. Hardly 10,000. Given that in 4000BC there would be much less of an ability to outfit such an expedition (since I doubt their ability to preserve food was as well developed, so they would be mostly living off the land), and you're probably talking about initial colonists of maybe a couple dozen people, tops. Once they find a good spot, *then* more people start joining them and a city develops. But that takes maybe 20 years - the time of one ancient-age turn. When, historically, have you read about people founding fully developed cities all at once? They started small. If they were government financed, you'd get maybe 100 people. If they weren't, then you got stuff like you found in the old west - several families striking out on their own.
As for whether or not animals are likely to attack, yes, overpopulation of humans and destruction of their native habitat is one driving factor in animal attacks, but you're forgetting that most wild animals these days grow up with an instinctual fear of humanity - they're taught that we're dangerous. In 4000BC, many animals likely hadn't even *seen* a human, and would probably see them as relatively defenseless.
Way to dig thru a thread to find something to make a personal insult about