[ WP ] At some point in time , a mysterious phenomenon occurred in which everyone on earth was trapped within a 10km ( 6.2 mile ) radius of where they were standing , unable to move past their boundary .

Some time around the 1500's the great divide began. The scientists back then knew as much about what caused it as we do today. The only thing that is know is every scrap of earth was instantly and inexplicably divided into circles about 12.4 miles across. No human could could pass any of these boundaries, however objects and animals could still pass through. 
 The effects of this divide was instantaneous, fishermen were stuck at sea and died of thirst, populations of cities plummeted and trade ceased flowing in, every empires maps and lands were reduced to a simple circle- all equal in size. Messages and information could still brought via. pigeons and paper drifted through wind. After a few short years attempts to reunite people ceased as everyone realized this was the world now. 
 As attempts of unification ceased diversification began. The current year is 1985, and my land was a lucky one. Here in Venice there was an immediate population dip as trade and food ceased flowing in, but the culture present in the Renaissance stayed with to the present day. Sciences and art flourished here, but not so everywhere. Every circle was its own human experiment; some, like ours, flourished in science and culture, others have devolved to the stone age. Most have become completely desolate of humans. We know this because we've been taking over the others. 
 As it turns out the circles only extended to the atmosphere, an impossible height to achieve then, but with current space flight we can go to other circles. We've been bombing the other scientifically advanced ones before the achieve space flight too. After all, once the division began we were only united by our home cirlce 

