Part I: This essay is the first in our week-long series on geopolitics by Hal Brands, the Henry A. Kissinger Distinguished Professor of Global Affairs at the Johns Hopkins University and a senior fellow at the American Enterprise Institute. You can read part two here, part three here, and part four here, and part five here.

Since the early 1900s, Eurasia — that giant landmass running from Europe’s Atlantic coastline to the Pacific shores of Asia — has been the cockpit of global rivalry. The major showdowns in international affairs have been intense, and often violent, clashes over control of the Eurasian continent and its maritime approaches. Ambitious land powers have reached for global hegemony by unifying the world’s strategic core under their control; the preeminent sea powers have sought to keep the world balanced by keeping Eurasia fragmented. The hot wars, cold wars, and proxy wars that characterized the twentieth century were merely chapters in this longer story. The American rivalry with China is now playing out against the same tableau.

We often think of the current period in global politics as the age of American power. In reality, we’re all living in a long Eurasian century.

Beijing may seem like a hyper-modern superpower, as it strives to harness advanced technologies for purposes of oppression at home and expansion abroad. But it is merely following the path of prior tyrannies that dreamed of achieving an unassailable geopolitical position—and so its conduct has revived a familiar nightmare for strategists in the democratic world.

If we want to understand the Eurasian century, the place to start is exploring why that supercontinent became the epicenter of the geopolitical earthquakes that defined the modern era. The best answer, remarkably, was provided as that era was just beginning.

Sir Halford Mackinder (1861 – 1947) has as solid a claim as anyone to having invented the field of geopolitics—the study of how geography interacts with statecraft and the competition for power. That’s perhaps not surprising, given his intellect and background.

Mackinder was a capacious thinker who became an Oxford professor at age twenty-five, on the strength of an essay that helped establish geography as an academic field. He had, remarked one contemporary, an ability to ‘get away from the details of everyday politics’ and ‘see things as a whole.’ During his upbringing, he had watched Great Britain and Russia jockey for imperial influence around the margins of Eurasia; he saw the rise of new powers, especially Germany and America, begin disrupting the equilibrium held since Napoleon’s defeat. In a famous lecture delivered to the Royal Geographic Society in 1904, Mackinder provided the defining explanation of the deep historical forces that shaped the Eurasian century.

First was the end of the ‘Columbian epoch’ — that 400-year age of exploration and imperial expansion. By 1900, the great empires had mapped and divided the world. Most of Africa and much of Asia were subjugated; there was, Mackinder wrote, ‘scarcely a region left for the pegging out of a claim of ownership, unless the result of a war between civilized or half-civilized powers.’ Mackinder’s country, Great Britain, had profited more than any other from that orgy of aggrandizement. Yet the implications were still, in his view, ominous.

The great European powers had, since Napoleon’s demise, mostly avoided all-out military clashes in part because expansion directed their geopolitical energies outward. A ‘long war’ against less sophisticated societies had facilitated a ‘long peace’ among the empires themselves. Now, however, the world was becoming claustrophobic — which would make collisions between the powers more frequent and jarring. As Mackinder put it, ‘Every explosion of social forces, instead of being dissipated in a circuit of unknown space and barbaric chaos, will be sharply re-echoed from the far side of the globe.’ A closed system was likely to be a violent one.

Second, technology was altering the meaning of geography. During the Columbian epoch, the mobility of sea power had exceeded that of land power, thanks to revolutions first in sail and then in steam. The discovery or construction of shortcuts — chiefly, the Suez Canal and the route around the Cape of Good Hope — had accentuated that advantage. The world’s naval powers, chiefly Britain, had thus been able to encircle Eurasia, grabbing footholds in the Middle East, India, and China. They were also able to negate the advantages that great land powers, namely Russia, enjoyed by virtue of their central geographic position.

Russia may have possessed interior lines during the Crimean War in the 1850s, but it hardly made a difference. Britain and France used their command of the sea to threaten Russia on multiple fronts from the Black Sea to the Baltic. Russian technological backwardness — the empire lacked railways anywhere south of Moscow — prevented it from responding quickly or concentrating its forces decisively. It took merely three weeks for allied troops to be sent from their home countries to the front lines in Crimea; it took three months for Russian troops stationed in Moscow to arrive in the south.

Yet now the technological pendulum was swinging in the other direction. The wars of German unification from 1864-1871 had shown how a dense network of railways, properly employed, could enable military victory and geopolitical expansion. The completion of the Trans-Siberian Railroad in 1904, the same year Mackinder delivered his lecture, created an infrastructure for projecting power from one end of Eurasia to the other. Russia, meanwhile, was industrialising rapidly: In 1900, it was producing fifty times as much coal and 2,000 times as much steel as it had in 1860. By the early twentieth century, that empire was tightening its grip on areas from Central Asia to Siberia.

All of which raised the possibility that a strategically located state could claim primacy over the world’s greatest landmass and the resources it contained. ‘The Pivot region of the world’s politics,’ Mackinder hypothesised, was ‘that vast area of Euro-Asia which is inaccessible to ships, but in antiquity lay open to the horse-riding nomads, and is today about to be covered with a network of railways.’

That hegemony was unlikely to be benign, thanks to a dimly visible development that would feature more prominently in Mackinder’s later writings: the emergence of modern totalitarian states. Tyrannies had always existed, indeed predominated, but the twentieth century saw something even more pernicious—the rise of countries that fused domestic repression, industrial dynamism, and violent expansion. It would be the Bolshevik regime, after it seized power in 1917, that provided Mackinder with a glimpse of how a ruthless, well-organised government could promote break-neck modernisation and harness the resulting power for its geopolitical designs. That regime also demonstrated, as would the fascist powers in the 1930s and 1940s, how the most horrific forms of political violence and the most aggressive visions of Eurasian expansion went hand-in-hand.

The strategic implications of such expansion, Mackinder had understood, were not just regional but global. Eurasian consolidation could threaten even those countries located beyond seemingly endless oceanic expanses.

Eurasia, as Mackinder pointed out, was three times the size of North America. It possessed two-thirds of the world’s population and the vast majority of its industrial potential. A country that dominated that landmass could overawe any potential competitor. Freed from threats on its borders, it could turn to building navies without peer. Continental domination could, then, be a springboard to maritime control: ‘The oversetting of the balance of power’ within Eurasia, wrote Mackinder, would also endanger the balance of power beyond it, for this ‘would permit of the use of vast continental resources for fleet-building, and the empire of the world would then be in sight.’

Thus Mackinder’s final insight — that global politics would henceforth revolve around desperate contests between onshore contenders and offshore balancers. Continental powers would seek preponderant influence in the great pivot area as well as the ‘inner crescent’— the ring of peripheral countries, from China to India to Western Europe, running around the Eurasian core. Sea powers would seek to maintain the balance by supporting ‘bridgeheads’ along the Eurasian periphery, allying with threatened onshore powers, and harassing an aspiring hegemon with operations on land and at sea. As Eurasian powers pushed outward, their enemies —within and beyond that continent — would work fiercely to hem them in.

Among those holding the line would be the United States. Mackinder envisioned London playing the predominant balancing role, as it had for centuries. But he acknowledged that America was poised to assume greater responsibility — because, ironically, it had already accomplished just what Mackinder feared.

During the nineteenth century, the United States had — thanks to fortuitous geography, skillful diplomacy, and outright conquest — created a continental domain stretching from the Atlantic to the Pacific. It had created a basis for power-projection, both across and beyond the continent, by building the transcontinental railroad and — the year before Mackinder gave his 1904 lecture—acquiring the Panama Canal route. America had also developed a cadre of strategic thinkers, such as Alfred Thayer Mahan, who anticipated Mackinder in warning that US security would be endangered if any hostile power commanded Europe or Asia. And, having won supremacy in North America, it began making its influence felt globally, whether by seizing the Philippines in 1898 or building the battleships that Theodore Roosevelt would send around the world a decade later.

Not the least of the factors that made the Eurasian century was the rise of a superpower in the New World that was committed to preventing consolidation of powers in the Old World.

When Mackinder proposed his thesis at a meeting of the Royal Geographical Society in 1904, he elicited questions and rejoinders. Hadn’t the Columbian epoch seen its own challenges to the balance of power in Europe, from Philip II, Louis XIV, and Napoleon? Wouldn’t the emergence of air transport eventually overshadow both land power and sea power? Was Russia, a late-modernising country still ruled by an absolute monarchy, really about to become a geopolitical juggernaut?

The critics had a point, for the moment, about Russia.  In the near-term, the construction of the Trans-Siberian Railroad did accompany a push into Manchuria and Korea. Yet that led only to a humiliating military defeat by Japan, and then to an unsuccessful revolution that served as a dress rehearsal for a successful one. For two generations thereafter, attempts at Eurasian domination came not from a pivot state pushing outward, but from peripheral powers—Germany and Japan—that struck deep into the Eurasian heartland while also striking out across the neighbouring seas.

In response, Mackinder would tinker with his thesis, equivocating on whether he saw Russia or Germany as the greater danger. During World War II, a Dutch-American intellectual, Nicholas Spykman, would invert Mackinder, claiming that it was ‘rimland’ — his term for the ‘crescent’—control of the ‘heartland’ that was most worrying. ‘Who controls the rimland rules Eurasia,’ he wrote; ‘who rules Eurasia controls the destinies of the world.’ Mackinder himself would come around to something closer to Spykman’s view in his last major essay, written in 1943 — just as Germany’s defeat and the ascendance of a hyper-empowered Soviet Union was making his original thesis look prescient after all.

Yet if the nuances of Mackinder’s argument were contested, the central theme was dead-on. Eurasia became a geopolitical hot-house in the twentieth century for many of the reasons Mackinder identified. The closing off of strategic safety values thrust the great powers against each other. The march of technology began to shrink Eurasia’s sprawling geography. The emergence of totalitarian states with modern industrial economies at their disposal fuelled aggression and conquest. All this served to pit a series of potential Eurasian hegemons against liberal superpowers; Britain and then America, whose freedom and security depended on dashing those designs.

The brutal clarity of Mackinder’s thesis was that the stars were aligning for persistent, high-stakes struggle over Eurasia and the world beyond. The brutal history of the subsequent century would show how right he was. All of the greatest wars and rivalries of the modern era have simply been contests to rule Mackinder’s world.