If you want to know what Russia, China or Iran will do next, don't read their newspapers or ask what our spies have dug up—consult a map. Geography can reveal as much about a government's aims as its secret councils. More than ideology or domestic politics, what fundamentally defines a state is its place on the globe. Maps capture the key facts of history, culture and natural resources. With upheaval in the Middle East and a tumultuous political transition in China, look to geography to make sense of it all.

As a way of explaining...