For centuries, the contest for global dominance has been inextricably linked to geography and the civilizations that have thrived within it. From the Heartland to the seas, geopolitical competition has revolved around the control of critical spaces and the strategic advantages they confer. Theories of geopolitics provide frameworks for understanding these dynamics. Halford Mackinder’s Heartland Theory posited that control over Eurasian interior—the ‘pivot area’— was the key fulcrum to global dominance (Mackinder 1904). Later, Alfred Thayer Mahan, in contrast, shifted the paradigm to the oceans, arguing that naval supremacy was the foundation of global influence (Mahan 1890). This principle remains relevant in many ways, as the United States continues to rely on sea power for its power projection aiming at global dominance. These theories shaped centuries of strategic thinking, guiding the policies of empires and superpowers alike. Mackinder’s ideas underpinned Cold War containment policies, while Mahan’s principles informed British and American naval dominance.
In the 21st century, neither the Heartland nor the seas alone can explain the complexities of current global competition as the world transitions into an era of intensified great power competition and multipolarity. Instead, Nicholas Spykman’s Rimland Theory—which highlights the coastal periphery encircling Eurasia—is the dominant framework for understanding modern geopolitics (Spykman 1944). The Rimland is where land power meets the sea power. It acts as the bridge between land and sea, housing critical natural resources, rapidly growing economies, and a significant portion of the world’s population. The region also hosts vital sea lanes and chokepoints, such as the Strait of Malacca, the Suez Canal, and the Bab-el-Mandeb, essential for global trade and energy flows. As the U.S.-led Western sea power confronts the land power coalition of China, Russia, Iran, and North Korea, the Rimland is increasingly becoming the ultimate battleground where the future of the world order will be determined. In the 21st century, the Rimland is not just a geographic space but the geopolitical fulcrum that will shape the balance of power for decades to come.
Heartland: The Core of Ancient Power
Control over the Eurasian Heartland enabled empires to dominate global power center of gravity in ancient and pre-modern times because of its unparalleled geographic and strategic advantages. Spanning Central Asia, Eastern Europe, and parts of Siberia—the Heartland provided immense natural resources, fertile lands, and access to critical trade routes like the Silk Road (Frankopan 2015). These routes connected the Heartland to wealthy civilizations in the Middle East, South Asia, and China, facilitating economic growth and cultural exchange. The ability to control this region not only ensured access to key resources but also allowed empires to regulate trade flows, taxing merchants and enriching their treasuries. This geographic centrality gave Heartland powers a significant economic and logistical edge. The Heartland’s vast and defensible terrain also provided unparalleled security and strategic depth for empires. Its natural barriers—mountains, deserts, and expansive steppes—made it difficult for external adversaries to penetrate.
This security allowed Heartland-based powers, such as the Mongol Empire and later the Russian Empire, to consolidate their rule and focus on outward expansion. From this secure base, empires could project power across Eurasia, conquering peripheral regions and establishing dominance over their neighbors. The Mongols, for example, used their control of the Heartland to build the largest contiguous empire in history, enabling the free flow of goods, technology, and ideas between East and West (. The Russian Empire similarly leveraged the Heartland to expand westward into Europe and eastward into Asia, utilizing its geographic depth to repel invasions from Napoleon and Hitler. For the Ottoman Empire, straddling the intersection of Europe, Asia, and the Middle East, capitalized on its control over the eastern portion of the Heartland to dominate trade and secure strategic chokepoints like the Bosporus and Dardanelles. This enabled the Ottomans to influence both regional and global politics for centuries.
Mackinder famously encapsulated Heartland’s strategic value: “Who rules East Europe commands the Heartland; who rules the Heartland commands the World Island; who rules the World Island commands the World” (Mackinder 1919). Even after the Industrial Revolution enabled Britain to achieve unparalleled naval supremacy, the geopolitical focus remained on controlling the heartland. The two World Wars and the subsequent Cold War reinforced this dynamic. The Soviet Union’s control of Eastern Europe and Central Asia epitomized Mackinder’s thesis, while the United States adopted George F. Kennan’s containment strategy through NATO and the Marshall Plan, to counter Soviet expansion. For the collective West, preventing the emergence of a singular power to establish an absolute dominance over Eurasian heartland has been a cornerstone of grand strategy, as control over the heartland confers the ability to shape global order (Kenan 1947). Yet, the advent of maritime exploration, trade, airpower and industrialized naval warfare has shifted the economic and strategic center of gravity to global sea routes. Over 90% of global commerce flows through maritime channels, diminishing the Heartland’s centrality in a globalized world. The Age of Exploration introduced a new dimension to geopolitical competition: sea power (Kaplan 2014).
Sea Power: The Engine of Modern Domination
The Age of Exploration marked a shift from land-based empires to maritime dominance. Alfred Thayer Mahan’s Sea Power Theory articulated the strategic importance of controlling the oceans, arguing that naval supremacy was essential for securing trade routes, projecting power, and maintaining global influence. His dictum, “Whoever rules the waves rules the world,” became a guiding principle for maritime powers (Freedman 2003). The emergence of sea power in the modern era transformed the dynamics of global dominance by enabling empires to project power far beyond their continental boundaries. Control of the seas provided unparalleled mobility, allowing navies to protect trade routes, establish colonies, and exert influence across vast territories. During the Age of Exploration, sea power became synonymous with empire-building, as maritime nations like Portugal and Spain leveraged their fleets to establish global trade networks and colonial outposts. The ability to command the seas enabled these empires to control the flow of goods, resources, and wealth, giving them a strategic advantage over their landlocked rivals. Maritime supremacy also facilitated the exchange of ideas and technologies, fostering the cultural and economic dominance that underpinned their global power.
In the 19th century, sea power reached its zenith with the rise of the British Empire, which epitomized Alfred Thayer Mahan’s theory that dominance over sea lanes was critical for global influence. The British Navy secured control of key chokepoints like the Suez Canal and the Strait of Malacca, ensuring access to trade routes that connected the empire’s far-flung colonies (Buzan and Waever 2003). This naval supremacy allowed Britain to dominate global commerce and maintain a position as the world’s preeminent power. The interconnectedness of trade and naval strength created a feedback loop: economic prosperity funded a powerful navy, while the navy safeguarded trade routes, enabling further economic growth.
The United States adopted and expanded upon this maritime strategy in the 20th century, establishing a global presence through its control of both the Atlantic and Pacific Oceans. The U.S. Navy’s ability to project power ensured victory in World War II and solidified its role as a superpower during the Cold War. Naval dominance allowed the U.S. to deter rivals, secure critical energy supplies, and enforce the liberal international order. Control over the seas remains a cornerstone of U.S. global strategy, enabling it to safeguard global trade, maintain alliances, and counter emerging threats in key regions like the Indo-Pacific (Allison 2017). In modern times, sea power has proven indispensable for nations seeking to shape the world order and maintain global primacy. However, the dominance of sea power is no longer absolute. The proliferation of anti-access/area denial (A2/AD) systems, hypersonic weapons, under and over the water UAVs and cyber capabilities has eroded traditional naval advantages. For instance, China’s militarization of the South China Sea demonstrates how rival powers challenge U.S. maritime supremacy (Storey 2016). These developments underscore the limitations of sea power in the 21st century.
Modern Constraints on Competition
The rivalry between the U.S.-led West and the coalition of China, Russia, Iran, and North Korea is inevitable due to structural and ideological divides. The West defends a liberal, rules-based order that has been created by them after the WWII, while its challengers seek to reshape global balance of power with alternative governance models and regional dominance. Geopolitical realities, including China’s rise, Russia’s assertiveness, and a group of capable middle powers such as Iran or North Korea, fuel this competition. Their overlapping vision and shared opposition to Western hegemony ensure that this rivalry will remain central to the emerging multipolar world order, shaping the balance of power and the future of global stability.
In the 21st century, the future of world order is no longer dictated solely by dominance over land or sea power. The emergence of nuclear weapons has profoundly reshaped the dynamics of great power competition. The doctrine of Mutually Assured Destruction (MAD) ensures that direct conflict between nuclear-armed states would lead to catastrophic consequences. Over the 79 years of nuclear weapons’ existence, there has been no instance of full-scale war between nuclear-armed states, despite their fierce rivalry. As a result, great power rivalry has shifted to indirect arenas, such as proxy wars, economic sanctions, and technological competition. Historical events like the Cuban Missile Crisis and contemporary U.S.-China tensions over Taiwan illustrate how nuclear deterrence influences the strategic behavior of major powers (Erickson and Martinson 2019).
In the current geopolitical landscape, despite the intense rivalry between China-Russia-led land powers and US-led Western sea powers, an all-out war remains highly unlikely. This makes non-nuclear zones a key battleground for great power competition. While vast landmasses and seas are protected by nuclear umbrellas, significant portions of the rimland remain beyond this safeguard. As a result, conflicts in these nuclear-free areas are less likely to escalate into nuclear war. This dynamic incentivizes nuclear powers to settle their rivalries through proxy conflicts in the rimland, where the outcomes of indirect confrontations can reshape the global balance of power without the risk of triggering a nuclear Armageddon. Furthermore, given the symmetry between the two blocs across nearly all domains—ranging from military and economic power to population, space, and high-tech advancements—it is improbable that either side could achieve a decisive victory in an all-out war, rendering direct conflict futile.
Economic interdependence further limits the ability of land or sea power to dictate global dominance. Globalization has deeply intertwined the economies of rivals like the United States and China, particularly in regions like the Rimland, where trade flows and supply chains are critical. Any disruption in these economic networks would carry significant costs for all parties, making the balance of economic power just as important as control of physical spaces. On the other hand, China is the largest trading partner for many Indo-Pacific nations, while the U.S. dollar underpins the global financial system. Disruptions to these networks would carry significant costs for all parties, incentivizing economic competition over outright conflict (Khanna 2016).
Technological advancements and the rise of hybrid warfare have increasingly blurred the traditional distinctions between land and sea power. The proliferation of modern weaponry such as UAVs, hypersonic precision missiles, and cyber capabilities has created multidimensional battlefields where asymmetric tactics play a dominant role, and achieving a decisive power advantage no longer guarantees absolute victory on the battlefield. Examples such as Russia’s cyber operations against Ukraine, Houthi and Hezbollah attacks on Israel, and the use of information warfare underscore the growing influence of hybrid warfare in reshaping geopolitical rivalries (Navarro 2015).
Rimland: The Battleground of the 21st Century & The Future of World Order
Nicholas Spykman’s Rimland Theory provides the most relevant framework for understanding modern geopolitics. Spanning the coastal periphery of Eurasia, the Rimland bridges land and sea power, encompassing critical maritime chokepoints, dynamic economies, and large populations. Spykman argued that control of the Rimland was essential for dominating Eurasia and, by extension, the world (Spykman 1938). In the context of 21st century’s geopolitics, the Rimland emerges as the decisive arena where the future of global power will be contested. Spanning the coastal regions of Eurasia, the Rimland represents the intersection of land and sea power, blending their strategic advantages and vulnerabilities. It houses critical maritime chokepoints such as the Strait of Malacca, the Suez Canal, and the Bab-el-Mandeb, which are essential for global trade and energy flows. Simultaneously, it provides access to the Heartland, allowing land powers to project influence outward. This dual function makes the Rimland the key battleground where control over global resources, trade, and influence will be decided.
Unlike the Heartland or the high seas, the Rimland hosts the world’s most dynamic economies, significant populations, and rapidly growing technological hubs. Regions like South Asia, Southeast Asia, the Middle East, and Eastern Europe are not only strategically located but also politically fragmented, creating opportunities for great powers to engage in influence campaigns and proxy conflicts. China’s Belt and Road Initiative (BRI) underscores the Rimland’s strategic importance. The BRI integrates overland corridors through Central Asia with maritime routes across the Indian Ocean, extending Beijing’s influence across the Eurasian periphery (Taylor 2018). Meanwhile, the United States has strengthened its presence in the Indo-Pacific through alliances like the Quad and AUKUS, aiming to counterbalance China’s rise and secure maritime freedom (Mahbubani 2018). Ultimately, the Rimland represents a convergence point where land and sea power compete, yet neither can achieve unilateral dominance. It is not merely a geographic space but the geopolitical fulcrum where the balance of power is determined. Control of the Rimland enables access to global markets, secures vital resources, and ensures influence over critical political and economic networks.
A group of middle and regional powers, including Turkey, Indonesia, Iran, Pakistan, India, Malaysia, Bangladesh, and Myanmar, adds further complexity to global dynamics. These states leverage their strategic locations to assert autonomy, often positioning themselves as pivotal players in the broader contest between land and sea powers. Notably, the rimland is home to one of the world’s most prominent civilizations—Islamic civilization, which boasts the second-largest number of followers globally. While these nation states do not act as a unified entity as they did during the medieval period under the gunpowder empires, they often share overlapping interests and perceive common threats as great power rivalry intensifies. This dynamic is not new; since the Industrial Revolution, the Islamic world has often been a victim of great power competition. The Cold War serves as a recent example, with Afghanistan becoming a battleground that ultimately contributed to the Soviet Union’s collapse.
As the contest between land and sea powers escalates, rimland countries are poised to find themselves once again caught in the crossfire. However, they also hold the potential to shape not only regional dynamics but the global balance of power, transforming from battlegrounds into influential players on the world stage.
Conclusion
From the Heartland of ancient empires to the seas of modern navies, geopolitical competition has always revolved around control of strategic spaces. In the 21st century, the Rimland emerges as the ultimate battleground. Its combination of geographic centrality, economic dynamism, strategic chokepoints, and the civilizational identity makes it the key to global dominance. As great powers vie for influence, Spykman’s assertion that “Who controls the Rimland rules Eurasia” resonates more than ever. The Rimland is not merely a theater of competition but the decisive determinant of the future world order. In the 21st century, as the world becomes increasingly multipolar and interconnected, the Rimland—not the Heartland or the seas—will shape the contours of the future world order.
References
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Mahbubani, Kishore. 2018. Has the West Lost It? A Provocation. London: Penguin Books.
Further Reading on E-International Relations