Geopolitical theory examines the relationship between geography, politics, and international relations. Key thinkers in geopolitical theory include:
- Alfred Thayer Mahan (1890) who argued that naval power was essential for trade and that countries with long coastlines and access to key sea lanes would be most powerful.
- Halford Mackinder (1904) who developed the heartland theory that whoever controlled the strategically located heartland region of Eurasia would control the world.
- Nicholas Spykman (1940s) argued that the inner crescent region (Western Europe, Middle East, South Asia, Southeast Asia) known as the rimland was most important, as it provided access to both sea and