Perhaps most importantly, the Mongol empire inextricably linked Europe and Asia and ushered in an era of frequent and extended contacts between East and West. And once the Mongols had achieved relative stability and order in their newly acquired domains, they neither discouraged nor impeded relations with foreigners.
Explanation: There are more rivers and mountains that connect through the east causing them to create state lines. There is also population density as well i.e there are more people spread out throughout Utah or Wyoming than New York or Rhode Island.