As long as we are looking at the world and environment 5767 (actually 5768 now) years ago I don't see how it is off topic.
The facts are that we are finding new indications almost daily that by 5000 or so years ago most of the basics that define human civilization, trade, pottery, agriculture, community projects, art, technology was not just beginning but had spread all over the globe.
Immigration has been a problem
Since 1607!