Why are some states strong, and others weak? Why are some powers on the rise in the international system, while other ones are on a downward trajectory? World history since the modern state-system took shape has seen incessant political-military competition for the control of valuable territory and resources. In the history of the long run, nothing has proven to be more unstable than borders. The role of human and physical geography in determining crucial advantages and disadvantages for sea and land powers has been a constant preoccupation for scholars, strategists, and political leaders alike. Global competition spurred political-geographical research and gave birth to classical geopolitical thought at the dawn of the 20th century. Geopolitics has since then become a fashionable term. Analysts, decision-makers, diplomats, and journalists alike employ the concept of geopolitics more and more often since the end of the Cold War.